Remove Greg Lehey's X11 section. It has served us well.

There are some gaps in the content now but those will be filled in
shortly. As far as I can tell, this was the last part of the Handbook
where the copyright was held by an individual author. I wonder if
people like iUniverse.com contacted Greg before publishing the
Handbook.

While I'm here add a standard synposis and mark up some attributions
in <sectNinfo>.

Partially submitted by: nik (posting on -doc)