Org.hs: remove misleading comment

This comment is likely copied from RST.hs where 'refs' variable indeed exists, but makes no sense here.

src/Text/Pandoc/Writers/Org.hs

@@ -71,7 +71,6 @@ pandocToOrg (Pandoc meta blocks) = do
                meta
   body <- blockListToOrg blocks
   notes <- liftM (reverse . stNotes) get >>= notesToOrg
-  -- note that the notes may contain refs, so we do them first
   hasMath <- liftM stHasMath get
   let main = render colwidth $ foldl ($+$) empty $ [body, notes]
   let context = defField "body" main