Add multiple enforcers docs.

README.md

@@ -35,6 +35,7 @@ All you need to learn to use `Casbin` first.
   * [Using a middleware](#using-a-middleware)
     * [basic Enforcer Middleware](#basic-enforcer-middleware)
     * [HTTP Request Middleware ( RESTful is also supported )](#http-request-middleware--restful-is-also-supported-)
+  * [Multiple enforcers](#multiple-enforcers)
   * [Using artisan commands](#using-artisan-commands)
   * [Cache](#using-cache)
 * [Thinks](#thinks)
@@ -274,6 +275,44 @@ Route::group(['middleware' => ['http_request']], function () {
 });
 ```
 
+### Multiple enforcers
+
+If you need multiple permission controls in your project, you can configure multiple enforcers.
+
+In the lauthz file, it should be like this:
+
+```php
+return [
+    'default' => 'basic',
+
+    'basic' => [
+        'model' => [
+            // ...
+        ],
+
+        'adapter' => Lauthz\Adapters\DatabaseAdapter::class,
+        // ...
+    ],
+
+    'second' => [
+        'model' => [
+            // ...
+        ],
+
+        'adapter' => Lauthz\Adapters\DatabaseAdapter::class,
+        // ...
+    ],
+];
+
+```
+
+Then you can choose which enforcers to use.
+
+```php
+Enforcer::guard('second')->enforce("eve", "articles", "edit");
+```
+
+
 ### Using artisan commands
 
 You can create a policy from a console with artisan commands.