Add crc16 verify type

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/HOWTO b/HOWTO
index 3bda021..e693d7a 100644
--- a/HOWTO
+++ b/HOWTO
@@ -577,6 +577,9 @@
 			crc32	Use a crc32 sum of the data area and store
 				it in the header of each block.
 
+			crc16	Use a crc16 sum of the data area and store
+				it in the header of each block.
+
 			null	Only pretend to verify. Useful for testing
 				internals with ioengine=null, not for much
 				else.