Update custom-domain.md

CName support for Enteprise Grade Edge

Author: BandaruDheeraj

articles/static-web-apps/custom-domain.md

@@ -11,6 +11,10 @@ ms.author: wujia
 
 # Custom domains with Azure Static Web Apps
 
+> [!NOTE]
+> Custom domain validation for Enterprise Grade Edge Static Web Apps now requires TXT token method - CNAME validation no longer supported for new domains
+
+
 By default, Azure Static Web Apps provides an autogenerated domain name for your website, but you can point a custom domain to your site. Free SSL/TLS certificates are automatically created for the autogenerated domain name and any custom domains you may add.
 
 When you map a custom domain to a static web app, you have a few options available, which include configuring subdomains and an apex domain.