Adding imports to docs

docs/api-guide/permissions.md

@@ -88,7 +88,9 @@ using the `APIView` class based views.
 
 Or, if you're using the `@api_view` decorator with function based views.
 
-    from rest_framework.decorators import permission_classes
+    from rest_framework.decorators import api_view, permission_classes
+    from rest_framework.permissions import IsAuthenticated
+    from rest_framework.response import Response
 
     @api_view('GET')
     @permission_classes((IsAuthenticated, ))