appendix/whymb: Add Quick Quiz on invalidate acknowledgments

Appendix C.4.2 ("Invalidate Queues and Invalidate Acknowledge") is
a bit abrupt, and cause readers some angst.  So add a Quick Quiz to
explain things.  Probably causing even more angst, but so it goes...

Reported-by: Philipp Stanner <stanner@posteo.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
1 file changed