fix CLI instruciotns

Author: cachai2

articles/container-apps/ingress-how-to.md

@@ -149,6 +149,9 @@ Disable ingress for your container app by omitting the `ingress` configuration p
 
 You can expose additional TCP ports from your application. To learn more, see the [ingress concept article](ingress-overview.md#additional-tcp-ports).
 
+> [Note]
+> To use this preview feature, you must have the containerapp CLI extension. Run `az extension add -n containerapp` in order to install the latest version of the containerapp CLI extension.
+
 
 ::: zone pivot="azure-cli"