Update how-to-assign-roles.md

Author: rastala

articles/machine-learning/how-to-assign-roles.md

@@ -30,15 +30,18 @@ In this article, you learn how to manage access (authorization) to an Azure Mach
 
 ## Default roles
 
-Azure Machine Learning workspaces have a four built-in roles that are available by default. When adding users to a workspace, they can be assigned one of the built-in roles described below.
+Azure Machine Learning workspaces have a five built-in roles that are available by default. When adding users to a workspace, they can be assigned one of the built-in roles described below.
 
 | Role | Access level |
 | --- | --- |
 | **AzureML Data Scientist** | Can perform all actions within an Azure Machine Learning workspace, except for creating or deleting compute resources and modifying the workspace itself. |
+| **AzureML Compute Operator** | Can create, manage and access compute resources within workspace.|
 | **Reader** | Read-only actions in the workspace. Readers can list and view assets, including [datastore](how-to-access-data.md) credentials, in a workspace. Readers can't create or update these assets. |
 | **Contributor** | View, create, edit, or delete (where applicable) assets in a workspace. For example, contributors can create an experiment, create or attach a compute cluster, submit a run, and deploy a web service. |
 | **Owner** | Full access to the workspace, including the ability to view, create, edit, or delete (where applicable) assets in a workspace. Additionally, you can change role assignments. |
 
+You can combine the roles to grant different levels of access. For example, you can grant a workspace user both **AzureML Data Scientist** and **Azure ML Compute Operator** role to permit the user to perform experiments while creating computes in self-service manner.
+
 > [!IMPORTANT]
 > Role access can be scoped to multiple levels in Azure. For example, someone with owner access to a workspace may not have owner access to the resource group that contains the workspace. For more information, see [How Azure RBAC works](../role-based-access-control/overview.md#how-azure-rbac-works).