Update v2-service-tiers-overview.md

ADO https://dev.azure.com/msft-skilling/Content/_workitems/edit/326827

Author: dlepow

articles/api-management/v2-service-tiers-overview.md

@@ -45,6 +45,7 @@ The v2 tiers are supported in API Management API version **2023-05-01-preview**
 
 ### Supported regions
 The v2 tiers are available in the following regions:
+* East US
 * East US 2
 * South Central US
 * North Central US