Added links to overview from topline tocs

Author: mbender-ms

articles/application-gateway/overview.md

@@ -28,7 +28,7 @@ This type of routing is known as application layer (OSI layer 7) load balancing.
 > * To do transport layer load balancing, review [Load Balancer](../load-balancer/load-balancer-overview.md). 
 > 
 > Your end-to-end scenarios may benefit from combining these solutions as needed.
-> For an Azure load-balancing options comparison, see [Overview of load-balancing options in Azure](/azure/architecture/guide/technology-choices/load-balancing-overview).
+> For an overview of the load balancing and content delivery services in Azure, see [Load Balancing and Content Delivery](../networking/load-balancer-content-delivery/load-balancing-content-delivery-overview.md).
 
 
 ## Features

articles/application-gateway/toc.yml

@@ -7,6 +7,8 @@
     href: overview.md
   - name: Application Gateway v2
     href: overview-v2.md
+  - name: What is load balancing and content delivery?
+    href: /azure/networking/load-balancer-content-delivery/load-balancing-content-delivery-overview?toc=/azure/application-gateway/toc.json&bc=/azure/application-gateway/breadcrumb/toc.json
   - name: Application Gateway for Containers
     href: ./for-containers/overview.md
   - name: Create Application Gateway - Portal

articles/frontdoor/TOC.yml

@@ -10,6 +10,8 @@
     href: /azure/well-architected/service-guides/azure-front-door?toc=/azure/frontdoor/TOC.json
   - name: Front Door best practices
     href: best-practices.md
+  - name: What is load balancing and content delivery?
+    href: /azure/networking/load-balancer-content-delivery/load-balancing-content-delivery-overview?toc=/azure/frontdoor/TOC.json
   - name: Choosing the right load balancer
     href: /azure/architecture/guide/technology-choices/load-balancing-overview?toc=/azure/frontdoor/TOC.json
   - name: FAQ

articles/frontdoor/front-door-overview.md

@@ -20,6 +20,9 @@ Azure Front Door is Microsoft's advanced cloud Content Delivery Network (CDN) de
 
 [!INCLUDE [ddos-waf-recommendation](../../includes/ddos-waf-recommendation.md)]
 
+>[!NOTE]
+> Azure Front Door is one of the services that make up the Load Balancing and Content Delivery category in Azure. Other services in this category include [Azure Load Balancer](../load-balancer/load-balancer-overview.md) and [Azure Application Gateway](../application-gateway/overview.md). Each service has its own unique features and use cases. For more information on this service category, see [Load Balancing and Content Delivery](/articles/networking/load-balancer-content-delivery/load-balancing-content-delivery-overview.md).
+
 ## Why use Azure Front Door?
 
 > [!VIDEO https://www.youtube.com/embed/-4FQYxV9mAE]