Add crc32c checksum

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/HOWTO b/HOWTO
index 503cd0f..f569f56 100644
--- a/HOWTO
+++ b/HOWTO
@@ -661,6 +661,9 @@
 				area and store it in the header of each
 				block.
 
+			crc32c	Use a crc32c sum of the data area and store
+				it in the header of each block.
+
 			crc32	Use a crc32 sum of the data area and store
 				it in the header of each block.