Added extra information and user-action summaries to 7 migration docs. (#6850)

* Added extra information and user-action summaries to 7 migration docs.

* Update docs/source/migrate_to_notebook7.md

Co-authored-by: Jeremy Tuloup <[email protected]>

* Update docs/source/migrate_to_notebook7.md

Co-authored-by: Jeremy Tuloup <[email protected]>

* Updated nbclassic messaging.

* Revised heading.

* Updated heading.

* Formatting pass.

---------

Co-authored-by: Jeremy Tuloup <[email protected]>

Author: ericsnekbytes

docs/source/migrate_to_notebook7.md

@@ -1,27 +1,62 @@
 # Migrating to Notebook 7
 
-```{warning}
-The Jupyter Notebook application is undergoing a major refactoring to
-improve the user experience and to make it easier to maintain and extend.
+_Updated 2023-04-24_
 
-This set of migration guides are intended to help you migrate your Classic Notebook
-setup and extensions to the new Jupyter Notebook 7, which is built on top of JupyterLab 4.
+```{warning}
+The Jupyter Notebook application's newest version 7 upgrade might break your
+extensions or other customizations, please read more below to find out if you
+need to take any actions to ensure a smooth, uninterrupted experience
 ```
 
-## Sunrising the Jupyter Notebook 7
+A major upgrade to the Jupyter Notebook interface is coming with Notebook 7! This
+upgrade will bring a heap of new features, but will also break backwards
+compatibility with many classic Notebook features and customizations.
+
+This set of guides is here to help you migrate your Classic Notebook setup and
+extensions to the new Notebook 7.
+
+## What you need to do
+
+For users who don't use extensions or other customizations, you will seamlessly
+receive the new Notebook 7 when you `pip install notebook` once version 7 is
+released out of beta, along with all its new features, like realtime
+collaboration, debugger, and theming.
+
+For users who need to use extensions or other customizations, you have a couple
+of options:
+
+- Look for Notebook 7 compatible versions of the extensions you already use,
+  and [find replacements for those that are not available]
+
+- If you need to maintain compatibility with the Classic Notebook for extensions
+  or other customizations that are critical to your workflows, you can switch to
+  [nbclassic], which will provide compatibility with the old notebook interface
+  and support during an intermediate transition period to Notebook 7
+
+## Why a new version?
 
-For the past few years, the Classic Jupyter Notebook has been in maintenance mode.
+For the past few years, the Classic Jupyter Notebook has been in maintenance
+mode.
 
-Development has mostly moved to alternative user interfaces like JupyterLab, which is a more
-modern and extensible web application. This has resulted in a lot of new
-features and improvements in JupyterLab, but also in a lot of new features and
-improvements that were not possible to integrate to the Classic Notebook.
+Development has mostly moved to alternative user interfaces like JupyterLab,
+which is a more modern and extensible web application. This has resulted in
+a lot of new features and improvements in JupyterLab, but also in a lot of
+new features and improvements that were not possible to integrate to the
+Classic Notebook.
 
-For a while the plan was to progressively _sunset_ the Classic Notebook and not maintain it anymore. However, the Classic Notebook is still widely used and it is still the default user interface for Jupyter in many scenarios. Many users and organizations have not been able to switch to JupyterLab yet. For some users, JupyterLab can also be a more complex environment to use, especially for beginners.
+For a while the plan was to progressively _sunset_ the Classic Notebook and
+not maintain it anymore. However, the Classic Notebook is still widely used
+and it is still the default user interface for Jupyter in many scenarios.
+Many users and organizations have not been able to switch to JupyterLab yet.
+For some users, JupyterLab can also be a more complex environment to use,
+especially for beginners.
 
-Following the feedback from the community, it was decided late 2021 to continue developing the Jupyter Notebook application and _sunrise_ it as Notebook 7. Notebook 7 is built on top of JupyterLab components and delivers new features like realtime collaboration, debugger, and theming.
+Following the feedback from the community, it was decided late 2021 to
+continue developing the Jupyter Notebook application and _sunrise_ it as
+Notebook 7.
 
-You can find more details about the changes currently taking place in the Jupyter Ecosystem in the [JEP 79] and [team-compass note].
+You can find more details about the changes currently taking place in the
+Jupyter Ecosystem in the [JEP 79] and [team-compass note].
 
 ## New features in Notebook 7
 
@@ -44,3 +79,5 @@ migrating/multiple-interfaces.md
 
 [jep 79]: https://jupyter.org/enhancement-proposals/79-notebook-v7/notebook-v7.html
 [team-compass note]: https://github.com/jupyter/notebook-team-compass/issues/5#issuecomment-1085254000
+[find replacements for those that are not available]: https://jupyter-notebook.readthedocs.io/en/latest/migrating/frontend-extensions.html#jupyterlab-equivalent-extensions-to-the-classic-notebook
+[nbclassic]: https://github.com/jupyter/nbclassic