Less of LID and OpenID in the YADIS spec

[Martin Atkins]

I think this capability discovery protocol is the core of YADIS, but
also due to the way it's written is also the main source of confusion
about what YADIS is trying to achieve. This section basically reads like
"Retrieve the URL and it'll either an be OpenID or LID URL, which you
can determine by the type of document retrieved".

Let's remove the specific mentions of OpenID and LID from that core bit
of text (perhaps move the OpenID and LID migration stuff to an
appendix?) and just say that the user either specifies the URL of an
identity server directly or do a document pointing to one. That way
people will get less confused about what exactly is going on here.