sched: fix documentation reference for sched_min_granularity_ns

Impact: documentation fix

sched-design-CFS.txt wrongly references sched_granularity_ns sysctl,
as its name in fact is sched_min_granularity_ns.
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Documentation/scheduler/sched-design-CFS.txt

@@ -92,7 +92,7 @@ other HZ detail.  Thus the CFS scheduler has no notion of "timeslices" in the
 way the previous scheduler had, and has no heuristics whatsoever.  There is
 only one central tunable (you have to switch on CONFIG_SCHED_DEBUG):
 
-   /proc/sys/kernel/sched_granularity_ns
+   /proc/sys/kernel/sched_min_granularity_ns
 
 which can be used to tune the scheduler from "desktop" (i.e., low latencies) to
 "server" (i.e., good batching) workloads.  It defaults to a setting suitable