man entry for --zero-metadata command

Signed-off-by: Adam Rutkowski <[email protected]>

utils/casadm.8

@@ -154,6 +154,10 @@ Atomic mode exploits extended NVMe metadata features. In this mode namespace
 uses 520 bytes LBA allowing to write cache data and metadata in a single
 request (atomically).
 
+.TP
+.B --zero-metadata
+Remove metadata from previously used cache device.
+
 .TP
 .B -H, --help
 Print help.
@@ -586,6 +590,15 @@ Identifier of cache instance <1-16384>.
 Defines output format for printed IO class configuration. It can be either
 \fBtable\fR (default) or \fBcsv\fR.
 
+.SH Options that are valid with --zero-metadata are:
+.TP
+.B -d, --device <DEVICE>
+Path to block device containing Open CAS metadata.
+
+.TP
+.B -f, --force
+Ignore potential dirty data on cache device.
+
 .SH Command --help (-H) does not accept any options.
 .BR