[PATCH] Documentation update for relay interface

Here's updated documentation for the relay interface, rewritten to match
the relayfs->relay changes.  It also moves relayfs.txt to relay.txt in the
process.

It includes the changes to relayfs.txt previously posted by Randy Dunlap,
thanks for those.

The relay-apps examples have also been updated to match, and can be found
on the sourceforge relayfs website.

Signed-off-by: Tom Zanussi <zanussi@us.ibm.com>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>