add known issue

Author: vhorne

articles/firewall/overview.md

@@ -6,7 +6,7 @@ ms.service: firewall
 services: firewall
 ms.topic: overview
 ms.custom: mvc, contperf-fy21q1
-ms.date: 01/04/2022
+ms.date: 01/18/2022
 ms.author: victorh
 # Customer intent: As an administrator, I want to evaluate Azure Firewall so I can determine if I want to use it.
 ---
@@ -93,7 +93,8 @@ Azure Firewall has the following known issues:
 | Error encountered when creating more than 2000 rule collections. | The maximal number of NAT/Application or Network rule collections is 2000 (Resource Manager limit). | This is a current limitation. |
 |Unable to see Network Rule Name in Azure Firewall Logs|Azure Firewall network rule log data does not show the Rule name for network traffic.|A feature is being investigated to support this.|
 |XFF header in HTTP/S|XFF headers are overwritten with the original source IP address as seen by the firewall. This is applicable for the following use cases:<br>- HTTP requests<br>- HTTPS requests with TLS termination|A fix is being investigated.|
-| Firewall logs (Resource specific tables - Preview) | Resource specific log queries are in preview mode and aren't currently supported. | A fix is being investigated. |
+| Firewall logs (Resource specific tables - Preview) | Resource specific log queries are in preview mode and aren't currently supported. | A fix is being investigated.|
+|Availability Zones for Firewall Premium in the Southeast Asia region|You can't currently deploy Azure Firewall Premium with Availability Zones in the Southeast Asia region.|Deploy the firewall in Southeast Asia without Availability Zones, or deploy in a region that supports Availability Zones.|
 
 ## Next steps