Update 3.gates.md

Author: GautierDele

content/4.digging-deeper/3.gates.md

@@ -38,3 +38,45 @@ class UserResource extends Resource
     // ...
 }
 ```
+
+## Policy message in gates
+
+You are able to get policies message if you want to be more explicit about why the policy is not passing, you first need to set the 
+config `rest.gates.message.enabled` to true. Be aware that this will change the gates format
+
+In your policy you need to return a policy message:
+
+```php
+use App\Models\Post;
+use App\Models\User;
+use Illuminate\Auth\Access\Response;
+ 
+/**
+ * Determine if the given post can be updated by the user.
+ */
+public function update(User $user, Post $post): Response
+{
+    return $user->id === $post->user_id
+        ? Response::allow()
+        : Response::deny('You do not own this post.');
+}
+```
+
+and this will result in the change of the `search` gating format:
+
+```json
+{
+  "data": [
+    {
+      "id": 1,
+      "name": "Lou West",
+      "gates": {
+        "authorized_to_update": {
+          "allowed": false,
+          "message": "You do not own this post."
+        }
+      }
+    }
+  ]
+}
+```