Public preview: Azure SignalR Service Premium Tier

Azure SignalR Service Premium Tier provides key capabilities to enable important enterprise scenarios. This includes: * Adding resiliency to your SignalR Service instances through Azure [availability zone](https://docs.microsoft.com/en-us/azure/azure-signalr/availability-zones) support * Ensuring high availability using SignalR Service’s [disaster recovery](https://docs.microsoft.com/en-us/azure/azure-signalr/signalr-concept-disaster-recovery) functionality * Easily scale up and down to meet capacity needs and optimize resource usage with [autoscale](https://docs.microsoft.com/en-us/azure/azure-signalr/signalr-howto-scale-autoscale) * Azure SignalR Service * Features * [ Azure SignalR Service](https://azure.microsoft.com/en-gb/products/signalr-service/)