Fixed #11959 -- Updated the tutorial to ensure that the admin site continues...

Fixed #11959 -- Updated the tutorial to ensure that the admin site continues to work after URLpatterns are introduced. Thanks to carljm for the report and draft patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@11621 bcc190cf-cafb-0310-a4f2-bffc1f526a37