Update reference-yaml-compute-instance.md

adding managed identity to docs

Author: jesscioffi

articles/machine-learning/reference-yaml-compute-instance.md

@@ -42,6 +42,9 @@ The source JSON schema can be found at https://azuremlschemas.azureedge.net/late
 | `network_settings` | object | Network security settings. | | |
 | `network_settings.vnet_name` | string | Name of the virtual network (VNet) when creating a new one or referencing an existing one. | | |
 | `network_settings.subnet` | string | Either the name of the subnet when creating a new VNet or referencing an existing one, or the fully qualified resource ID of a subnet in an existing VNet. Do not specify `network_settings.vnet_name` if the subnet ID is specified. The subnet ID can refer to a VNet/subnet in another resource group. | | |
+| `identity` | object | The managed identity configuration to assign to the compute. AmlCompute clusters support only one system-assigned identity or multiple user-assigned identities, not both concurrently. | | |
+| `identity.type` | string | The type of managed identity to assign to the compute. If the type is `user_assigned`, the `identity.user_assigned_identities` property must also be specified. | `system_assigned`, `user_assigned` | |
+| `identity.user_assigned_identities` | array | List of fully qualified resource IDs of the user-assigned identities. | | |
 
 ## Remarks