[gentoo-doc] Removing obsolete guides

[Josh Saddler]

I'd like to remove the obsolete guides in /doc/en/. They're all properly
marked with disclaimer="obsolete", and with the exception of
nx-guide.xml, none of them appear in list.xml. They don't work anymore
and have no business cluttering up our tree. Redirects are pointless too
for these old docs, as any links that may have existed to them elsewhere
on the net are years out of date.

Any objections?