feat(dns): allow setting an externally managed cluster domain

cmd/uc/dns/root.go

@@ -7,11 +7,13 @@ import (
 func NewRootCommand() *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "dns",
-		Short: "Manage cluster domain in Uncloud DNS.",
-		Long: "Manage cluster domain in Uncloud DNS.\n" +
+		Short: "Manage the cluster domain.",
+		Long: "Manage the cluster domain.\n" +
 			"DNS commands allow you to reserve or release a unique 'xxxxxx.uncld.dev' domain for your " +
 			"cluster. When reserved, Caddy service deployments will automatically update DNS records to route " +
-			"traffic to the services in the cluster.",
+			"traffic to the services in the cluster.\n\n" +
+			"EXPERIMENTAL: Use 'uc dns set' to configure an externally managed domain instead. " +
+			"Uncloud does not manage DNS records for manually set domains.",
 	}
 	cmd.AddCommand(
 		NewReleaseCommand(),