doc: Document rcutorture forward-progress test kernel parameters

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

Documentation/admin-guide/kernel-parameters.txt

@@ -3773,6 +3773,23 @@
 			Set wait time between force_quiescent_state bursts
 			in seconds.
 
+	rcutorture.fwd_progress= [KNL]
+			Enable RCU grace-period forward-progress testing
+			for the types of RCU supporting this notion.
+
+	rcutorture.fwd_progress_div= [KNL]
+			Specify the fraction of a CPU-stall-warning
+			period to do tight-loop forward-progress testing.
+
+	rcutorture.fwd_progress_holdoff= [KNL]
+			Number of seconds to wait between successive
+			forward-progress tests.
+
+	rcutorture.fwd_progress_need_resched= [KNL]
+			Enclose cond_resched() calls within checks for
+			need_resched() during tight-loop forward-progress
+			testing.
+
 	rcutorture.gp_cond= [KNL]
 			Use conditional/asynchronous update-side
 			primitives, if available.