Fixed #7897 -- Corrected some spelling and grammatical errors in the...

Fixed #7897 -- Corrected some spelling and grammatical errors in the InlineModelAdmin objects documentation. Thanks arthurk and Karen Tracey for catching these.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8065 bcc190cf-cafb-0310-a4f2-bffc1f526a37