add caveat

Author: greg-lindsay

articles/application-gateway/application-gateway-diagnostics.md

@@ -6,7 +6,7 @@ services: application-gateway
 author: greg-lindsay
 ms.service: azure-application-gateway
 ms.topic: concept-article
-ms.date: 06/17/2024
+ms.date: 05/07/2025
 ms.author: greglin 
 ---
 
@@ -81,7 +81,7 @@ Activity logging is automatically enabled for every Resource Manager resource. Y
    For Application Gateway, three logs are available:
 
    * Access log
-   * Performance log
+   * Performance log (available only for the v1 SKU)
    * Firewall log
 
 1. To start collecting data, select **Turn on diagnostics**.