Fixed #10553 -- Corrected several uses of `URLconf` in documentation and...

Fixed #10553 -- Corrected several uses of `URLconf` in documentation and comments, according to the Django style guide.  Based on patch from rduffield.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@10256 bcc190cf-cafb-0310-a4f2-bffc1f526a37