Fixed #15614 -- Fixed potentially confusing URLconf examples in...

Fixed #15614 -- Fixed potentially confusing URLconf examples in docs/ref/generic-views.txt by adding explicit import statement and using function passing instead of strings in the URLpattern

git-svn-id: http://code.djangoproject.com/svn/django/trunk@15822 bcc190cf-cafb-0310-a4f2-bffc1f526a37