add nexus owner rbac role documentation

Author: John

articles/operator-nexus/concepts-security-access-identity.md

@@ -118,4 +118,12 @@ and updating baremetal machine (BMM) and baseboard management (BMC) keysets.
 | Microsoft.NetworkCloud/clusters/bareMetalMachineKeySets/write  | Create a new or update an existing bare metal machine key set of the provided cluster              |
 | Microsoft.NetworkCloud/clusters/bmcKeySets/read                | Get baseboard management controller key set of the provided cluster                                |
 | Microsoft.NetworkCloud/clusters/bmcKeySets/write               | Create a new or update an existing baseboard management controller key set of the provided cluster |
-| Microsoft.NetworkCloud/clusters/bmcKeySets/delete              | Delete a baseboard management controller key set of the provided cluster
+| Microsoft.NetworkCloud/clusters/bmcKeySets/delete              | Delete a baseboard management controller key set of the provided cluster                           |
+
+### Operator Nexus Owner Role (Preview)
+
+The user with this role has access to perform all actions on any Microsoft.NetworkCloud resource.
+
+| Actions                  | Description                                             |
+|--------------------------|---------------------------------------------------------|
+| Microsoft.NetworkCloud/* | Perform any action on a Microsoft.NetworkCloud resource |