[#1684] cli: Correct description of control shards writecache seal

Signed-off-by: Alexander Chuprov <a.chuprov@yadro.com>

cmd/frostfs-cli/modules/control/writecache.go

@@ -24,7 +24,7 @@ var writecacheShardCmd = &cobra.Command{
 var sealWritecacheShardCmd = &cobra.Command{
 	Use:   "seal",
 	Short: "Flush objects from write-cache and move write-cache to degraded read only mode.",
-	Long:  "Flush all the objects from the write-cache to the main storage and move the write-cache to the degraded read only mode: write-cache will be empty and no objects will be put in it.",
+	Long:  "Flush all the objects from the write-cache to the main storage and move the write-cache to the 'CLOSED' mode: write-cache will be empty and no objects will be put in it.",
 	Run:   sealWritecache,
 }