Fixed #6890 -- Removed duplicate instruction to rename the `polls/detail.htm`...

Fixed #6890 -- Removed duplicate instruction to rename the `polls/detail.htm` template in tutorial part 4.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@7380 bcc190cf-cafb-0310-a4f2-bffc1f526a37