Fixed #15233 -- Corrected a duplicate module directive that raised a warning...

Fixed #15233 -- Corrected a duplicate module directive that raised a warning on newer versions of Sphinx. Thanks to Aryeh Leib Taurog for the report.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@15561 bcc190cf-cafb-0310-a4f2-bffc1f526a37