Update network-considerations.md

Hello, I'm making this extra clarification note in this documentation to help clarifying customer's doubt as it's been raised as a feedback.

Enabling the 'Remote gateway' setting will cause the Azure AD domain services to be in an unhealthy state.

Author: vrviriya

articles/active-directory-domain-services/network-considerations.md

@@ -42,7 +42,7 @@ As you design the virtual network for Azure AD DS, the following considerations
 
 A managed domain connects to a subnet in an Azure virtual network. Design this subnet for Azure AD DS with the following considerations:
 
-* A managed domain must be deployed in its own subnet. Don't use an existing subnet or a gateway subnet.
+* A managed domain must be deployed in its own subnet. Don't use an existing subnet or a gateway subnet. This includes the usage of remote gateways settings in the virtual network which puts the managed domain in an unsupported state.
 * A network security group is created during the deployment of a managed domain. This network security group contains the required rules for correct service communication.
     * Don't create or use an existing network security group with your own custom rules.
 * A managed domain requires 3-5 IP addresses. Make sure that your subnet IP address range can provide this number of addresses.
@@ -188,4 +188,4 @@ For more information about some of the network resources and connection options
 
 * [Azure virtual network peering](../virtual-network/virtual-network-peering-overview.md)
 * [Azure VPN gateways](../vpn-gateway/vpn-gateway-about-vpn-gateway-settings.md)
-* [Azure network security groups](../virtual-network/network-security-groups-overview.md)
+* [Azure network security groups](../virtual-network/network-security-groups-overview.md)