docs: improve User Provider

docs/concepts.md

@@ -13,6 +13,7 @@ This document covers some of the base concepts used throughout the library.
 
 Shield is designed so that the initial setup of your application can all happen in code with nothing required to be
 saved in the database. This means you do not have to create large seeder files that need to run within each environment.
+
 Instead, it can be placed under version control, though the Settings library allows those settings to be easily stored
 in the database if you create an interface for the user to update those settings.
 
@@ -24,25 +25,10 @@ on the standard Config class if nothing is found in the database.
 
 ## User Providers
 
-You can use your own models to handle user persistence. Shield calls this the "User Provider" class.
-A default model is provided for you by the `CodeIgniter\Shield\Models\UserModel` class. You can change
-this in the `Config\Auth::$userProvider` setting. The only requirement is that your new class
-MUST extend the provided `UserModel`.
-
-Shield has a CLI command to quickly create a custom `UserModel` class by running the following
-command in the terminal:
-
-```console
-php spark shield:model UserModel
-```
-
-The class name is optional. If none is provided, the generated class name would be `UserModel`.
-
-You should set `Config\Auth::$userProvider` as follows:
+Shield has a model to handle user persistence. Shield calls this the "User Provider" class.
+A default model is provided for you by the `CodeIgniter\Shield\Models\UserModel` class.
 
-```php
-public string $userProvider = \App\Models\UserModel::class;
-```
+You can use your own model to customize user attributes. See [Customizing Shield](./customization.md#custom-user-provider) for details.
 
 ## User Identities
 

docs/customization.md

@@ -8,6 +8,7 @@
   - [Custom Validation Rules](#custom-validation-rules)
     - [Registration](#registration)
     - [Login](#login)
+  - [Custom User Provider](#custom-user-provider)
 
 ## Route Configuration
 
@@ -181,3 +182,24 @@ Similar to the process for validation rules in the **Registration** section, you
         ],
     ];
 ```
+
+## Custom User Provider
+
+If you want to customize user attributes, you need to create your own
+[User Provider](./concepts.md#user-providers) class.
+The only requirement is that your new class MUST extend the provided `CodeIgniter\Shield\Models\UserModel`.
+
+Shield has a CLI command to quickly create a custom `UserModel` class by running the following
+command in the terminal:
+
+```console
+php spark shield:model UserModel
+```
+
+The class name is optional. If none is provided, the generated class name would be `UserModel`.
+
+After creating the class, set the `$userProvider` property in **app/Config/Auth.php** as follows:
+
+```php
+public string $userProvider = \App\Models\UserModel::class;
+```