Adds limitation

Author: chasewilson

articles/aks/azure-cni-overlay.md

@@ -101,6 +101,7 @@ Azure CNI Overlay has the following limitations:
     - Traffic from host network pods is not able to reach Windows Overlay pods.
 - Virtual Machine Scale Sets (VMAS) are not supported for Overlay
 - Dualstack networking is not supported in Overlay
+- You can't use [DCsv2-series](/azure/virtual-machines/dcv2-series) virtual machines in node pools. To meet Confidential Computing requirements, consider using [DCasv5 or DCadsv5-series confidential VMs](/azure/virtual-machines/dcasv5-dcadsv5-series) instead.
 
 ## Set up Overlay clusters