fix: tips for karmadactl help options

Signed-off-by: algebra2k <jackson.cloudnative@gmail.com>

pkg/karmadactl/cordon.go

@@ -60,6 +60,9 @@ func NewCmdCordon(cmdOut io.Writer, karmadaConfig KarmadaConfig, cmdStr string)
 		},
 	}
 
+	flags := cmd.Flags()
+	opts.AddFlags(flags)
+
 	return cmd
 }
 
@@ -83,6 +86,9 @@ func NewCmdUncordon(cmdOut io.Writer, karmadaConfig KarmadaConfig, cmdStr string
 		},
 	}
 
+	flags := cmd.Flags()
+	opts.AddFlags(flags)
+
 	return cmd
 }