dm raid: fixup documentation for discard support

Remove comment above parse_raid_params() that claims
"devices_handle_discard_safely" is a table line argument when it is
actually is a module parameter.

Also, backfill dm-raid target version 1.6.0 documentation.

Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Reviewed-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/Documentation/device-mapper/dm-raid.txt b/Documentation/device-mapper/dm-raid.txt
index ef8ba9f..85b74b1 100644
--- a/Documentation/device-mapper/dm-raid.txt
+++ b/Documentation/device-mapper/dm-raid.txt
@@ -224,3 +224,4 @@
 	New status (STATUSTYPE_INFO) fields: sync_action and mismatch_cnt.
 1.5.1   Add ability to restore transiently failed devices on resume.
 1.5.2   'mismatch_cnt' is zero unless [last_]sync_action is "check".
+1.6.0   Add discard support (and devices_handle_discard_safely module param).
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 88e4c7f..423e42e 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -477,8 +477,6 @@
  *                                      will form the "stripe"
  *    [[no]sync]			Force or prevent recovery of the
  *                                      entire array
- *    [devices_handle_discard_safely]	Allow discards on RAID4/5/6; useful if RAID
- *					member device(s) properly support TRIM/UNMAP
  *    [rebuild <idx>]			Rebuild the drive indicated by the index
  *    [daemon_sleep <ms>]		Time between bitmap daemon work to
  *                                      clear bits