edited networking hub and landing page to add NAT gateway

Author: asudbring

articles/networking/index.yml

@@ -102,6 +102,17 @@ additionalContent:
               url: ../route-server/quickstart-configure-route-server-portal.md
             - text: See more
               url: ../route-server/index.yml
+        
+        # Card
+        - title: Provide outbound connectivity to a virtual network
+          links:
+            - text: What is Azure Virtual Network NAT?
+              url: ../virtual-network/nat-gateway/overview.md
+            - text: Create and configure NAT gateway resource
+              url: ../virtual-network/nat-gateway/tutorial-create-nat-gateway-portal.md
+            - text: See more
+              url: ../virtual-network/nat-gateway/index.yml
+   
 
     - title: Application delivery services  # < 60 chars (optional)
       items: