ox-md: Do not define `org-md-publish-to-md' twice

* lisp/ox-md.el (ox-md-publish-to-md): Do not define function twice.

lisp/ox-md.el

@@ -484,17 +484,6 @@ FILENAME is the filename of the Org file to be published.  PLIST
 is the property list for the given project.  PUB-DIR is the
 publishing directory.
 
-Return output file name."
-  (org-publish-org-to 'md filename ".md" plist pub-dir))
-
-;;;###autoload
-(defun org-md-publish-to-md (plist filename pub-dir)
-  "Publish an org file to Markdown.
-
-FILENAME is the filename of the Org file to be published.  PLIST
-is the property list for the given project.  PUB-DIR is the
-publishing directory.
-
 Return output file name."
   (org-publish-org-to 'md filename ".md" plist pub-dir))