Added the comment regarding the supported regions

Added the comment that the target resources must be in one of the regions supported by the Azure Chaos Studio preview (https://azure.microsoft.com/en-us/global-infrastructure/services/?products=chaos-studio). Only those resources will be listed on the "Targets" blade.

Author: rseso

articles/chaos-studio/chaos-studio-limitations.md

@@ -15,6 +15,7 @@ During the public preview of Azure Chaos Studio, there are a few limitations and
 
 ## Limitations 
 
+* The target resources must be in [one of the regions supported by the Azure Chaos Studio Preview](https://azure.microsoft.com/en-us/global-infrastructure/services/?products=chaos-studio) 
 * For agent-based faults, the machine must have access to the following **HTTPS endpoints**:
     * http://agentcommunicationservice-frontdoor-canary.trafficmanager.net 
     * If sending telemetry data to Application Insights, the IPs [in this document](../azure-monitor/app/ip-addresses.md) are also required.