Merge pull request #606 from kenjis/fix-docs-flters

docs: remove unsupported Filter code sample

Author: kenjis

docs/authorization.md

@@ -9,7 +9,6 @@
       - [can()](#can)
       - [inGroup()](#ingroup)
       - [hasPermission()](#haspermission)
-      - [Authorizing via Filters](#authorizing-via-filters)
       - [Authorizing via Routes](#authorizing-via-routes)
   - [Managing User Permissions](#managing-user-permissions)
       - [addPermission()](#addpermission)
@@ -130,28 +129,34 @@ if (! $user->hasPermission('users.create')) {
 }
 ```
 
-#### Authorizing via Filters
+#### Authorizing via Routes
 
-You can restrict access to multiple routes through a [Controller Filter](https://codeigniter.com/user_guide/incoming/filters.html). One is provided for both restricting via groups the user belongs to, as well as which permission they need. The filters are automatically registered with the system under the `group` and `permission` aliases, respectively. You can define the protections within **app/Config/Filters.php**:
+You can restrict access to a route or route group through a
+[Controller Filter](https://codeigniter.com/user_guide/incoming/filters.html).
 
-```php
-public $filters = [
-    'group:admin,superadmin' => ['before' => ['admin/*']],
-    'permission:users.manage' => ['before' => ['admin/users/*']],
-];
-```
+One is provided for restricting via groups the user belongs to, the other
+is for permission they need. The filters are automatically registered with the
+system under the `group` and `permission` aliases, respectively.
 
-#### Authorizing via Routes
-
-The filters can also be used on a route or route group level:
+You can set the filters within **app/Config/Routes.php**:
 
 ```php
 $routes->group('admin', ['filter' => 'group:admin,superadmin'], static function ($routes) {
-    $routes->resource('users');
+    $routes->group(
+        '',
+        ['filter' => ['group:admin,superadmin', 'permission:users.manage']],
+        static function ($routes) {
+            $routes->resource('users');
+        }
+    );
 });
-
 ```
 
+Note that the options (`filter`) passed to the outer `group()` are not merged with the inner `group()` options.
+
+> **Note** If you set more than one filter to a route, you need to enable
+> [Multiple Filters](https://codeigniter.com/user_guide/incoming/routing.html#multiple-filters).
+
 ## Managing User Permissions
 
 Permissions can be granted on a user level as well as on a group level. Any user-level permissions granted will