Fixed #17538 -- corrected the section in tutorial 3 about the handler404...

Fixed #17538 -- corrected the section in tutorial 3 about the handler404 default. Thanks matt at brozowski dot com for the report.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17369 bcc190cf-cafb-0310-a4f2-bffc1f526a37