[docs] [issue18757] Fix internal references for concurrent modules

[Ezio Melotti]

Ezio Melotti added the comment:

Serhiy, seems you forgot to attach a patch.

----------
nosy: +ezio.melotti
type:  -> enhancement

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue18757>
_______________________________________