Wikipedia page on XRDS

I finally finished the longstanding action item to post a Wikipedia page on
XRDS. It took longer than I thought because there is really a lot to
communicate about this relatively simple format:

	http://en.wikipedia.org/wiki/XRDS 

Please review when you have time -- and improve it (that's what Wikipedia is
for!)

I also added links to this page to the Wikipedia pages on XRI, Yadis,
i-names, and XDI. Please update any others you can think of.

=Drummond