procfs-guide: drop pointless   entities

Having trailing   entities in a revision numer seems pretty pointless
to me.  More so, it's causing me pains, so just drop them since no other
guide is doing this.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>