docbook: update procfs credits

Update Erik Mouw's email address & affiliation in DocBook.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Erik Mouw <mouw@nl.linux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>