Update comments for groups in AuthGroups.php

The current comment content does not match what the code is doing. Please feel free to clean up or let me know any suggestions.

Thank you!

Author: iamsyh

src/Config/AuthGroups.php

@@ -20,10 +20,12 @@ class AuthGroups extends BaseConfig
      * --------------------------------------------------------------------
      * Groups
      * --------------------------------------------------------------------
-     * The available authentication systems, listed
-     * with alias and class name. These can be referenced
-     * by alias in the auth helper:
-     *      auth('api')->attempt($credentials);
+     * The available groups in the system. 
+     * Where the key is the group name, and the values are an 
+     * array of any additional fields you would like for that group.
+     * Whatever value you assign as the key, will be used to refer to the group when using functions such as:
+     *      $user->addGroup('superadmin')
+     * ref: https://github.com/codeigniter4/shield/blob/develop/docs/quickstart.md#change-available-groups for more info
      */
     public array $groups = [
         'superadmin' => [