Copy edited new docs in docs/model-api.txt from [4535]
Copy edited new docs in docs/model-api.txt from [4535]

--HG--
extra : convert_revision : svn%3Abcc190cf-cafb-0310-a4f2-bffc1f526a37/django/trunk%404539

Belgabor/django,Belgabor/django,Belgabor/django