Update subnet delegation message for consumption-only env

Clarify that subnet must not be delegated to any services including
Microsoft.App/environments.

Co-authored-by: Copilot <[email protected]>

Author: Rajneesh Mitharwal

articles/container-apps/custom-virtual-networks.md

@@ -74,7 +74,7 @@ Different environment types have different subnet requirements:
 
 - `/23` is the minimum subnet size required for virtual network integration.
 
-- Your subnet must not be delegated to any services.
+- Your subnet MUST NOT be delegated to any services, including `Microsoft.App/environments`.
 
 - The Container Apps runtime reserves a minimum of 60 IPs for infrastructure in your VNet. The reserved amount may increase up to 256 addresses as apps in your environment scale.