App Configuration now supports Azure Availability Zones

[Azure Availability zones(AZ)](https://docs.microsoft.com/azure/availability-zones/az-overview#availability-zones) are now supported by App Configuration in AZ-enabled regions. Each AZ-enabled region consists of 3 or more physically separated datacenters to protect against single datacenter failures. AZ are enabled for all existing and new App Configuration resources automatically at no extra cost. The current supported AZ-enabled regions are: East US, East US 2, Central US, West US 2, North Europe, West Europe, France Central, UK South, Southeast Asia, and Japan East. As more regions are added, please reference [the FAQ](https://docs.microsoft.com/azure/azure-app-configuration/faq#how-does-app-configuration-ensure-high-data-availability) for updates as well as the [azure guide](https://docs.microsoft.com/azure/availability-zones/az-region#azure-services-supporting-availability-zones) for more information on AZ-enabled regions in Azure.