Documentation:kernel-per-CPU-kthreads.txt: Remove reference to elevator=

This argument was not being considered since blk-mq was set by default,
so removed this documentation to avoid confusion.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com>

.txt file is now .rst
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Documentation/admin-guide/kernel-per-CPU-kthreads.rst

@@ -274,9 +274,7 @@ To reduce its OS jitter, do any of the following:
 		(based on an earlier one from Gilad Ben-Yossef) that
 		reduces or even eliminates vmstat overhead for some
 		workloads at https://lkml.org/lkml/2013/9/4/379.
-	e.	Boot with "elevator=noop" to avoid workqueue use by
-		the block layer.
-	f.	If running on high-end powerpc servers, build with
+	e.	If running on high-end powerpc servers, build with
 		CONFIG_PPC_RTAS_DAEMON=n.  This prevents the RTAS
 		daemon from running on each CPU every second or so.
 		(This will require editing Kconfig files and will defeat
@@ -284,12 +282,12 @@ To reduce its OS jitter, do any of the following:
 		due to the rtas_event_scan() function.
 		WARNING:  Please check your CPU specifications to
 		make sure that this is safe on your particular system.
-	g.	If running on Cell Processor, build your kernel with
+	f.	If running on Cell Processor, build your kernel with
 		CBE_CPUFREQ_SPU_GOVERNOR=n to avoid OS jitter from
 		spu_gov_work().
 		WARNING:  Please check your CPU specifications to
 		make sure that this is safe on your particular system.
-	h.	If running on PowerMAC, build your kernel with
+	g.	If running on PowerMAC, build your kernel with
 		CONFIG_PMAC_RACKMETER=n to disable the CPU-meter,
 		avoiding OS jitter from rackmeter_do_timer().