[WATCHDOG] clean-up watchdog documentation

Random sampling of some URLs in the Documentation tree to see how many were
stale found that one watchdog driver was now a porn site.  In fact if the
watchdogs document directory was any older it would be written in latin

Clean it up somewhat and add Last reviewed headers, something all the
Documentation could do with IMHO.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>