Fix CG description of module system

[David Kastrup]

I posted this patch already several days ago without any feedback, so I
tried uploading it on Rietveld in order to get a better reaction.  A bit
of a nuisance how much work it is to get even trivial doc improvements
accepted.

Unfortunately, my lack of expertise made it end up in a previous issue.
Since it is somewhat related to the previous issue and I don't know how
to clean the old issue and redo this as a new issue, I'll just post the
link of the last upload and pretend that this was my intent in the first
place.

I really don't think a turnaround time of weeks for things like that,
taking an order of magnitude more of time, effort, and spirit than
actually writing the improvement, contributes much to development.

<URL:http://codereview.appspot.com/160048>

-- 
David Kastrup