add doc install lumen framework

docs/_sidebar.md

@@ -3,6 +3,7 @@
     - [Introduction](README)
     - [Requirements](requirements)
     - [Installation](installation)
+    - [Lumen installation](lumen)
     - [Basic Usage](basic-usage)
     - [Upgrade Guide](upgrade-guide)
 

docs/lumen.md

@@ -0,0 +1,38 @@
+## Composer
+
+The recommended installation method is using [Composer](https://getcomposer.org/).
+
+In your project root just run:
+
+```bash
+composer req bavix/laravel-wallet
+```
+
+Ensure that you’ve set up your project to [autoload Composer-installed packages](https://getcomposer.org/doc/01-basic-usage.md#autoloading).
+
+## Add the service to the app
+
+[Editing the application file](https://lumen.laravel.com/docs/5.8/providers#registering-providers) `bootstrap/app.php`
+```php
+$app->register(\Bavix\Wallet\WalletServiceProvider::class);
+```
+
+Start the migration and use the library.
+
+## You can use it for customization
+
+Sometimes it is useful...
+
+### Run Migrations
+Publish the migrations with this artisan command:
+```bash
+php artisan vendor:publish --tag=laravel-wallet-migrations
+```
+
+### Configuration
+You can publish the config file with this artisan command:
+```bash
+php artisan vendor:publish --tag=laravel-wallet-config
+```
+
+After installing the package, you can proceed to [use it](basic-usage).