Fix AKS BC/DR doc to reference VMSS

Author: lastcoolnameleft

articles/aks/operator-best-practices-multi-region.md

@@ -11,7 +11,7 @@ ms.custom: fasttrack-edit
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 # Best practices for business continuity and disaster recovery in Azure Kubernetes Service (AKS)
 
-As you manage clusters in Azure Kubernetes Service (AKS), application uptime becomes important. AKS provides high availability by using multiple nodes in an availability set. But these multiple nodes don’t protect your system from a region failure. To maximize your uptime, plan ahead to maintain business continuity and prepare for disaster recovery.
+As you manage clusters in Azure Kubernetes Service (AKS), application uptime becomes important. By default, AKS provides high availability by using multiple nodes in a [Virtual Machine Scale Set (VMSS)](https://docs.microsoft.com/en-us/azure/virtual-machine-scale-sets/overview). But these multiple nodes don’t protect your system from a region failure. To maximize your uptime, plan ahead to maintain business continuity and prepare for disaster recovery.
 
 This article focuses on how to plan for business continuity and disaster recovery in AKS. You learn how to: