[1.0.X] Improved the model formset and inline formset documentation to be more...

[1.0.X] Improved the model formset and inline formset documentation to be more explicit and handle some cases that were never addressed before.

Backport of r9614 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@9615 bcc190cf-cafb-0310-a4f2-bffc1f526a37