Manual update for --continue option

Patch adds to mdadm man the following information:

 --continue
   This option is complementary pair to assembly --freeze-reshape option.
   It is needed when --grow operation is interrupted and it is not restarted
   automatically due to --freeze-reshape usage during array assembly.
   Option --continue has to be used together with -G , ( --grow ) command
   and device that it should be executed on.  All parameters required for
   reshape continuation will be read from array metadata.  If initial
   --grow command had required --backup-file= option to be set,
   continuation option will require to  have  exactly the same backup
   file pointed to also.

   Any other parameter passed together with --continue option will be ignored.

Signed-off-by: Adam Kwolek <adam.kwolek@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

mdadm.8.in

@@ -733,6 +733,31 @@ or layout.  See the GROW MODE section below on RAID\-DEVICES CHANGES.
 The file must be stored on a separate device, not on the RAID array
 being reshaped.
 
+.TP
+.BR \-\-continue
+This option is complementary to the
+.B \-\-freeze-reshape
+option for assembly. It is needed when
+.B \-\-grow
+operation is interrupted and it is not restarted automatically due to
+.B \-\-freeze-reshape
+usage during array assembly.  This option is used together with
+.BR \-G
+, (
+.BR \-\-grow
+) command and device for a pending reshape to be continued.
+All parameters required for reshape continuation will be read from array metadata.
+If initial
+.BR \-\-grow
+command had required
+.BR \-\-backup\-file=
+option to be set, continuation option will require to have exactly the same
+backup file given as well.
+.IP
+Any other parameter passed together with
+.BR \-\-continue
+option will be ignored.
+
 .TP
 .BR \-N ", " \-\-name=
 Set a