Update manage-with-azure-rbac.md

Added `Microsoft.Compute/virtualMachines/write` permission to minimum required permissions for the user-assigned managed identities to Register and manage existing SAP system.

Author: cwhitley-MSFT

articles/sap/center-sap-solutions/manage-with-azure-rbac.md

@@ -200,6 +200,7 @@ To register an existing SAP system and manage that system with Azure Center for
 | Minimum permissions for *user-assigned managed identities* |
 | ---------------------------------------------------------- |
 | `Microsoft.Compute/virtualMachines/read` |
+| `Microsoft.Compute/virtualMachines/write` |
 | `Microsoft.Compute/virtualMachines/extensions/read` |
 | `Microsoft.Compute/virtualMachines/extensions/write` |
 | `Microsoft.Compute/virtualMachines/extensions/delete` |