Fixed #10400: Added a note in the file uploads doc about the correct form type...

Fixed #10400: Added a note in the file uploads doc about the correct form type needed for file uploads to work.  Thanks claudep and timo.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@10816 bcc190cf-cafb-0310-a4f2-bffc1f526a37