Fixed #11137 -- Add missing base class in proxy model extra managers doc.  Thanks ekarulf.
Fixed #11137 -- Add missing base class in proxy model extra managers doc.  Thanks ekarulf.

--HG--
extra : convert_revision : svn%3Abcc190cf-cafb-0310-a4f2-bffc1f526a37/django/trunk%4010818

adieu/django-nonrel,adieu/django-nonrel,adieu/django-nonrel