Update create-service-group-member-rest-api.md

Author: kenieva

articles/governance/service-groups/create-service-group-member-rest-api.md

@@ -28,6 +28,8 @@ To add resources, resource groups, or subscriptions to a Service Group (preview)
 - If you haven't already, install [ARMClient](https://github.com/projectkudu/ARMClient). It's a tool
   that sends HTTP requests to Azure Resource Manager-based REST APIs.
 
+- To be able to deploy a service group member relationship, you must have Microsoft.Relationship/ServiceGroupMember/write permissions on the source as well as Microsoft.ServiceGroup Contributor at the target service group. 
+
 ## Create in REST API
 
 For REST API, use the