docs(aio): cleanup aalert, callout, subsection use and author style (angular#24986)

PR Close angular#24986

Author: sjtrimble

aio/content/guide/animations.md

@@ -22,7 +22,7 @@ code uses [AnimationBuilder](/api/animations/AnimationBuilder). If your code doe
 uncomment the `web-animations-js` polyfill from the `polyfills.ts` file generated by Angular CLI.
 </div>
 
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 The examples in this page are available as a <live-example></live-example>.
 
@@ -183,7 +183,7 @@ transition definitions, and not in a separate `state(void)` definition. Thus, th
 are different on enter and leave: the element enters from the left
 and leaves to the right.
 
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 These two common animations have their own aliases:
 

aio/content/guide/aot-compiler.md

@@ -4,7 +4,7 @@ The Angular Ahead-of-Time (AOT) compiler converts your Angular HTML and TypeScri
 
 This guide explains how to build with the AOT compiler using different compiler options and how to write Angular metadata that AOT can compile.
 
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   <a href="https://www.youtube.com/watch?v=kW9cJsvcsGo">Watch compiler author Tobias Bosch explain the Angular Compiler</a> at AngularConnect 2016.
 
@@ -39,7 +39,7 @@ For AOT compilation, append the `--aot` flags to the _build-only_ or the _build-
   ng serve --aot
 </code-example>
 
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 The `--prod` meta-flag compiles with AOT by default.
 
@@ -297,7 +297,7 @@ At the same time, the AOT **_collector_** analyzes the metadata recorded in the
 
 You can think of `.metadata.json` as a diagram of the overall structure of a decorator's metadata, represented as an [abstract syntax tree (AST)](https://en.wikipedia.org/wiki/Abstract_syntax_tree).
 
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 Angular's [schema.ts](https://github.com/angular/angular/blob/master/packages/compiler-cli/src/metadata/schema.ts)
 describes the JSON format as a collection of TypeScript interfaces.
@@ -333,7 +333,7 @@ Parentheses                        | `(a + b)`
 If an expression uses unsupported syntax, the _collector_ writes an error node to the `.metadata.json` file. The compiler later reports the error if it needs that
 piece of metadata to generate the application code.
 
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  If you want `ngc` to report syntax errors immediately rather than produce a `.metadata.json` file with errors, set the `strictMetadataEmit` option in `tsconfig`.
 

aio/content/guide/architecture-modules.md

@@ -26,7 +26,7 @@ Here's a simple root NgModule definition:
 
 <code-example path="architecture/src/app/mini-app.ts" region="module" title="src/app/app.module.ts" linenums="false"></code-example>
 
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   The `export` of `AppComponent` is just to show how to export; it isn't actually necessary in this example. A root NgModule has no reason to _export_ anything because other modules don't need to _import_ the root NgModule.
 
@@ -56,7 +56,7 @@ A component and its template together define a _view_. A component can contain a
 
 When you create a component, it is associated directly with a single view, called the _host view_. The host view can be the root of a view hierarchy, which can contain _embedded views_, which are in turn the host views of other components. Those components can be in the same NgModule, or can be imported from other NgModules. Views in the tree can be nested to any depth.
 
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     The hierarchical structure of views is a key factor in the way Angular detects and responds to changes in the DOM and app data. 
 </div>
 
@@ -72,7 +72,7 @@ Other JavaScript modules use *import statements* to access public objects from o
 
 <code-example path="architecture/src/app/app.module.ts" region="export" linenums="false"></code-example>
 
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+<div class="alert is-helpful">
   <a href="http://exploringjs.com/es6/ch_modules.html">Learn more about the JavaScript module system on the web.</a>
 </div>
 
@@ -99,7 +99,7 @@ In the example of the simple root module above, the application module needs mat
 
 In this way you're using both the Angular and JavaScript module systems _together_. Although it's easy to confuse the two systems, which share the common vocabulary of "imports" and "exports", you will become familiar with the different contexts in which they are used.
 
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   Learn more from the [NgModules](guide/ngmodules) page.
 

aio/content/guide/architecture.md

@@ -27,7 +27,7 @@ Like JavaScript modules, NgModules can import functionality from other NgModules
 
 Organizing your code into distinct functional modules helps in managing development of complex applications, and in designing for reusability. In addition, this technique lets you take advantage of _lazy-loading_—that is, loading modules on demand—in order to minimize the amount of code that needs to be loaded at startup.
 
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   For a more detailed discussion, see [Introduction to modules](guide/architecture-modules).
 
@@ -39,7 +39,7 @@ Every Angular application has at least one component, the *root component* that
 
 The `@Component` decorator identifies the class immediately below it as a component, and provides the template and related component-specific metadata.
 
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    Decorators are functions that modify JavaScript classes. Angular defines a number of such decorators that attach specific kinds of metadata to classes, so that it knows what those classes mean and how they should work.
 
@@ -59,7 +59,7 @@ Before a view is displayed, Angular evaluates the directives and resolves the bi
 
 Your templates can also use *pipes* to improve the user experience by transforming values for display. Use pipes to display, for example, dates and currency values in a way appropriate to the user's locale. Angular provides predefined pipes for common transformations, and you can also define your own.
 
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   For a more detailed discussion of these concepts, see [Introduction to components](guide/architecture-components).
 
@@ -74,7 +74,7 @@ For data or logic that is not associated with a specific view, and that you want
 
  *Dependency injection* (or DI) lets you keep your component classes lean and efficient. They don't fetch data from the server, validate user input, or log directly to the console; they delegate such tasks to services.
 
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   For a more detailed discusssion, see [Introduction to services and DI](guide/architecture-services).
 
@@ -96,7 +96,7 @@ The router interprets a link URL according to your app's view navigation rules a
 
 To define navigation rules, you associate *navigation paths* with your components. A path uses a URL-like syntax that integrates your program data, in much the same way that template syntax integrates your views with your program data. You can then apply program logic to choose which views to show or to hide, in response to user input and your own access rules.
 
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    For a more detailed discussion, see [Routing and navigation](guide/router).
 
@@ -128,7 +128,7 @@ Each of these subjects is introduced in more detail in the following pages.
   * [Pipes](guide/architecture-components#pipes)
 * [Services and dependency injection](guide/architecture-services)
 
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    Note that the code referenced on these pages is available as a <live-example></live-example>.
 </div>

aio/content/guide/attribute-directives.md

@@ -51,7 +51,7 @@ ng generate directive highlight
 
 The CLI creates `src/app/highlight.directive.ts`, a corresponding test file (`.../spec.ts`, and _declares_ the directive class in the root `AppModule`.
 
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 _Directives_ must be declared in [Angular Modules](guide/ngmodules) in the same manner as _components_.
 
@@ -71,7 +71,7 @@ Angular locates each element in the template that has an attribute named `appHig
 
 The _attribute selector_ pattern explains the name of this kind of directive.
 
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 #### Why not "highlight"?
 
@@ -146,7 +146,7 @@ each adorned by the `HostListener` decorator.
 The `@HostListener` decorator lets you subscribe to events of the DOM
 element that hosts an attribute directive, the `<p>` in this case.
 
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 Of course you could reach into the DOM with standard JavaScript and attach event listeners manually.
 There are at least three problems with _that_ approach:

aio/content/guide/browser-support.md

@@ -95,7 +95,7 @@ Angular supports most recent browsers. This includes the following specific vers
 
 </table>
 
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 Angular's continuous integration process runs unit tests of the framework on all of these browsers for every pull request,
 using <a href="https://saucelabs.com/">SauceLabs</a> and
@@ -154,7 +154,7 @@ add it yourself, following the same pattern:
 1. install the npm package
 1. `import` the file in `polyfills.ts`
 
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 Non-CLI users should follow the instructions [below](#non-cli).
 </div>

aio/content/guide/component-interaction.md

@@ -119,7 +119,7 @@ E2E tests of input property setter with empty and non-empty names:
 
 Detect and act upon changes to input property values with the `ngOnChanges()` method of the `OnChanges` lifecycle hook interface.
 
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+<div class="alert is-helpful">
 
 
 
@@ -311,7 +311,7 @@ The following example illustrates this technique with the same
 Neither its appearance nor its behavior will change.
 The child [CountdownTimerComponent](guide/component-interaction#countdown-timer-example) is the same as well.
 
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@@ -400,7 +400,7 @@ Each `AstronautComponent` is a child of the `MissionControlComponent` and theref
 
 
 
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aio/content/guide/component-styles.md

@@ -187,7 +187,7 @@ They are _not inherited_ by any components nested within the template nor by any
 
 </div>
 
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   You can specify more than one styles file or even a combination of `styles` and `styleUrls`.
 

aio/content/guide/dependency-injection-in-action.md

@@ -25,7 +25,7 @@ application and don't need to be listed in any module.
 Service classes can act as their own providers which is why defining them in the `@Injectable` decorator
 is all the registration you need.
 
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@@ -167,7 +167,7 @@ that is visible only to the component and its children, if any.
 You could also provide the `HeroService` to a *different* component elsewhere in the application.
 That would result in a *different* instance of the service, living in a *different* injector.
 
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@@ -433,7 +433,7 @@ It may already have that value in its internal container.
 If it doesn't, it may be able to make one with the help of a ***provider***.
 A *provider* is a recipe for delivering a service associated with a *token*.
 
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@@ -577,7 +577,7 @@ The second provider substitutes the `DateLoggerService` for the `LoggerService`.
 The `LoggerService` is already registered at the `AppComponent` level.
 When _this component_ requests the `LoggerService`, it receives the `DateLoggerService` instead.
 
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@@ -645,7 +645,7 @@ The `HeroOfTheMonthComponent` constructor's `logger` parameter is typed as `Mini
 Behind the scenes, Angular actually sets the `logger` parameter to the full service registered under the `LoggingService` token which happens to be the `DateLoggerService` that was [provided above](guide/dependency-injection-in-action#useclass).
 
 
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@@ -707,7 +707,7 @@ After some undisclosed work, the function returns the string of names
 and Angular injects it into the `runnersUp` parameter of the `HeroOfTheMonthComponent`.
 
 
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@@ -769,7 +769,7 @@ A ***class-interface*** should define *only* the members that its consumers are
 Such a narrowing interface helps decouple the concrete class from its consumers.
 
 
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@@ -866,7 +866,7 @@ and displays them in the order they arrive from the database.
 
 
 
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@@ -982,7 +982,7 @@ If you're lucky, they all implement the same base class
 whose API your `NewsComponent` understands.
 
 
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@@ -1165,7 +1165,7 @@ its class signature doesn't mention `Parent`:
 
 
 
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aio/content/guide/dependency-injection-pattern.md

@@ -81,7 +81,7 @@ now in the constructor.
 The `Car` class no longer creates an `engine` or `tires`.
 It just consumes them.
 
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 This example leverages TypeScript's constructor syntax for declaring
 parameters and properties simultaneously.
@@ -101,7 +101,7 @@ conform to the general API requirements of an `engine` or `tires`.
 
 Now, if someone extends the `Engine` class, that is not `Car`'s problem.
 
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 The _consumer_ of `Car` has the problem. The consumer must update the car creation code to
 something like this: