Remove '.model' shortcut from viewset docs. Refs encode#2486. Closes encode#2549.

Author: maryokhin

docs/api-guide/viewsets.md

@@ -178,7 +178,7 @@ The actions provided by the `ModelViewSet` class are `.list()`, `.retrieve()`,
 
 #### Example
 
-Because `ModelViewSet` extends `GenericAPIView`, you'll normally need to provide at least the `queryset` and `serializer_class` attributes, or the `model` attribute shortcut.  For example:
+Because `ModelViewSet` extends `GenericAPIView`, you'll normally need to provide at least the `queryset` and `serializer_class` attributes.  For example:
 
     class AccountViewSet(viewsets.ModelViewSet):
         """