Building documentation on linux

[Christopher Faylor]

I haven't been able to build the doc directory in winsup for some time,
after upgrading to a newer Red Hat Linux.  I finally figured out that I
needed this package:

docbook-dtd30-sgml-1.0-10.noarch.rpm

to build the cygwin documentation on linux.

This enabled me to do almost everything but I had to change a label in
cygwin/path.sgml because it was too long.  In the doc directory, I had
to add a space after the '-I' in some of the programs that took include
options, and I had to mess with the creation of faq.html a little.  I
also had to remove sites.texinfo from readme.texinfo (is this still used
for anything?).

Please let me know if I screwed up anything for any other platforms and
I'll try to fix it now that I have a tentative grasp on how this stuff
works.

cgf