Pages: Clarify DNS needs to be proxied for custom branch alias

Author: WalshyDev

src/content/docs/pages/how-to/custom-branch-aliases.mdx

@@ -14,9 +14,9 @@ This will allow you to have a custom domain that will always show the latest bui
 
 :::note
 
-Currently, this setup is only supported when using Cloudflare DNS.
+This setup is only supported when using a proxied Cloudflare DNS record.
 
-If you attempt to follow this guide using an external DNS provider, your custom alias will be sent to the production branch of your Pages project.
+If you attempt to follow this guide using an external DNS provider or an unproxied DNS record, your custom alias will be sent to the production branch of your Pages project.
 
 :::