torture: document --allcpus argument added to the kvm.sh script

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/testing/selftests/rcutorture/bin/kvm.sh

@@ -46,6 +46,7 @@ jitter="-1"
 
 usage () {
 	echo "Usage: $scriptname optional arguments:"
+	echo "       --allcpus"
 	echo "       --bootargs kernel-boot-arguments"
 	echo "       --bootimage relative-path-to-kernel-boot-image"
 	echo "       --buildonly"