enhance ilm show, add ilm update, rename modify to update everywhere (#58)

cmd/index.go

@@ -154,8 +154,8 @@ func IndexCreate(conf *cfg.Config, modify bool) *cli.Command {
 	usage := "create a new index"
 
 	if modify {
-		name = "modify"
-		usage = "modify anindex"
+		name = "update"
+		usage = "update an index"
 	}
 
 	return &cli.Command{