Update docs/api-guide/viewsets.md

Author: browniebroke

docs/api-guide/viewsets.md

@@ -128,7 +128,7 @@ You may inspect these attributes to adjust behavior based on the current action.
             permission_classes = [IsAdminUser]
         return [permission() for permission in permission_classes]
 
-**Note**: don't use the `action` attribute in the `get_parsers`, `get_authenticators` or `get_content_negotiator` methods, otherwise you will get an `AttributeError` error.
+**Note**: the `action` attribute is not available in the `get_parsers`, `get_authenticators` and `get_content_negotiator` methods, as it is set _after_ they are called in the framework lifecycle. If you override one of these methods and try to access the `action` attribute in them, you will get an `AttributeError` error.
 
 ## Marking extra actions for routing