fix: wrong cli description

Signed-off-by: xiaowu.zhu <xiaowu.zhu@daocloud.io>
(cherry picked from commit bf4d6f290b)

cmd/helm/plugin_install.go

@@ -39,8 +39,8 @@ This command allows you to install a plugin from a url to a VCS repo or a local
 func newPluginInstallCmd(out io.Writer) *cobra.Command {
 	o := &pluginInstallOptions{}
 	cmd := &cobra.Command{
-		Use:     "install [options] <path|url>...",
-		Short:   "install one or more Helm plugins",
+		Use:     "install [options] <path|url>",
+		Short:   "install a Helm plugin",
 		Long:    pluginInstallDesc,
 		Aliases: []string{"add"},
 		Args:    require.ExactArgs(1),