Update application-gateway-limits.md

SubscriptionUsage is captured per subscription per region and hence our logic is valid per subscription per region and not per subscription only.

Author: MJyot

includes/application-gateway-limits.md

@@ -7,7 +7,7 @@ ms.author: greglin
 ---
 | Resource | Limit | Note |
 | --- | --- | --- |
-| Azure Application Gateway |1,000 per subscription | |
+| Azure Application Gateway |1,000 per region per subscription | |
 | Frontend IP configurations |2 |1 public and 1 private |
 | Frontend ports |100<sup>1</sup> | |
 | Backend address pools |100 | |