documentation: Update RCU CPU stall warning messages

The RCU CPU stall warnings have morphed significantly since the last
update, so this commit brings the documentation up to date.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2017-08-17 12:29:22 -07:00
commit d3cf5176d0