Update overview.md

Author: Raphael Bickel

articles/azure-resource-manager/management/overview.md

@@ -77,7 +77,8 @@ There are some important factors to consider when defining your resource group:
 
 * When creating a resource group, you need to provide a location for that resource group. You may be wondering, "Why does a resource group need a location? And, if the resources can have different locations than the resource group, why does the resource group location matter at all?" The resource group stores metadata about the resources. When you specify a location for the resource group, you're specifying where that metadata is stored. For compliance reasons, you may need to ensure that your data is stored in a particular region.
 
-   If the resource group's region is temporarily unavailable, you can't update resources in the resource group because the metadata is unavailable. The resources in other regions will still function as expected, but you can't update them. For more information about building reliable applications, see [Designing reliable Azure applications](/azure/architecture/checklist/resiliency-per-service).
+   If the resource group's region is temporarily unavailable, you can't update resources in the resource group because the metadata is unavailable. The resources in other regions will still function as expected, but you can't update them. This doesn't apply to global resources, such as CDN, Traffic Manager or Azure Frontdoor.
+   For more information about building reliable applications, see [Designing reliable Azure applications](/azure/architecture/checklist/resiliency-per-service).
 
 * A resource group can be used to scope access control for administrative actions. To manage a resource group, you can assign [Azure Policies](../../governance/policy/overview.md), [Azure roles](../../role-based-access-control/role-assignments-portal.md), or [resource locks](lock-resources.md).