[1.1.X] Fixed #6047 -- Minor correction to the documentation regarding regex...

[1.1.X] Fixed #6047 -- Minor correction to the documentation regarding regex field lookups. Thanks to Richard D. Worth for the suggestion, and Steve Holden for the text.

Merge of r11541 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.1.X@11563 bcc190cf-cafb-0310-a4f2-bffc1f526a37