Tweak to custom roles text

Author: rolyon

articles/role-based-access-control/custom-roles.md

@@ -22,7 +22,7 @@ ms.custom: H1Hack27Feb2017
 
 If the [built-in roles for Azure resources](built-in-roles.md) don't meet the specific needs of your organization, you can create your own custom roles. Just like built-in roles, you can assign custom roles to users, groups, and service principals at subscription, resource group, and resource scopes.
 
-Custom roles are stored in an Azure Active Directory (Azure AD) directory and can be shared across subscriptions. Each directory can have up to **5000** custom roles. (For specialized clouds, such as Azure Government, Azure Germany, and Azure China 21Vianet, the limit is 2000 custom roles.) Custom roles can be created using Azure PowerShell, Azure CLI, or the REST API.
+Custom roles are defined at the Azure AD directory level and can be shared across subscriptions. Each directory can have up to **5000** custom roles. (For specialized clouds, such as Azure Government, Azure Germany, and Azure China 21Vianet, the limit is 2000 custom roles.) Custom roles can be created using Azure PowerShell, Azure CLI, or the REST API.
 
 ## Custom role example