rcu: RCU_TRACE enables event tracing as well as debugfs

The commit brings the RCU_TRACE Kconfig option's help text up to date
by noting that it enables additional event tracing as well as debugfs.
Signed-off-by: NNikolay Borisov <kernel@kyup.com>
[ paulmck:  Do some wordsmithing. ]
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>

lib/Kconfig.debug

@@ -1430,7 +1430,8 @@ config RCU_TRACE
 	select TRACE_CLOCK
 	help
 	  This option provides tracing in RCU which presents stats
-	  in debugfs for debugging RCU implementation.
+	  in debugfs for debugging RCU implementation.  It also enables
+	  additional tracepoints for ftrace-style event tracing.
 
 	  Say Y here if you want to enable RCU tracing
 	  Say N if you are unsure.