Link to xdmcp description

[Harold Hunt]

I found a good article for those out there that are having difficulties in
understanding what xdmcp is used for:
http://www.rru.com/~meo/pubsntalks/xrj/xdm.html

You must understand that each local client wishing to connect to a server
that is logged into a remote host via xdmcp needs to pass a -auth
%AUTHORITY_FILE% command line parameter, where %AUTHORITY_FILE% is a
reference to your .Xauthority file for the current session.  If you're
logged into a remote host, it is fairly unlikely that you are going to have
the %AUTHORITY_FILE% accesible on your local host.

Harold