From what I've seen on several c.l.p threads, some people have a tough
time figuring the correct 'args' argument to subprocess.Popen's
constructor. In an effort to cut down on such discussions in the future,
I've written the attached docs patch to better explain the subject.

I'm not an rst/Sphinx guru and thus was unable to actually test the
patch, so there might be some (hopefully minor) formatting errors.