Custom health probe update for Preview

Custom health probe update for Preview

Author: JackStromberg

articles/application-gateway/application-gateway-probe-overview.md

@@ -90,6 +90,10 @@ Once the match criteria is specified, it can be attached to probe configuration
 
 ## NSG considerations
 
+Fine grain control over the Application Gateway subnet via NSG rules is possible in public preview. More details can be found [here](application-gateway-private-deployment.md#network-security-group-control).
+
+With current functionality there are some restrictions:
+
 You must allow incoming Internet traffic on TCP ports 65503-65534 for the Application Gateway v1 SKU, and TCP ports 65200-65535 for the v2 SKU with the destination subnet as **Any** and source as **GatewayManager** service tag. This port range is required for Azure infrastructure communication.
 
 Additionally, outbound Internet connectivity can't be blocked, and inbound traffic coming from the **AzureLoadBalancer** tag must be allowed.