Update in core_drg_attachment_management.html.markdown

Author: jajaiswa

website/docs/r/core_drg_attachment_management.html.markdown

@@ -59,7 +59,7 @@ The following arguments are supported:
       For information about why you would associate a route table with a DRG attachment, see:
         * [Transit Routing: Access to Multiple VCNs in Same Region](https://docs.cloud.oracle.com/iaas/Content/Network/Tasks/transitrouting.htm)
         * [Transit Routing: Private Access to Oracle Services](https://docs.cloud.oracle.com/iaas/Content/Network/Tasks/transitroutingoracleservices.htm)
-    * `type` (Required)- The type can be one of these values: `IPSEC_TUNNEL`, `REMOTE_PEERING_CONNECTION`, `VIRTUAL_CIRCUIT`
+    * `type` (Required)- The type can be one of these values: `IPSEC_TUNNEL`, `REMOTE_PEERING_CONNECTION`, `VCN`,`VIRTUAL_CIRCUIT`
 * `route_table_id`(Optional)(Updatable) - The OCID of the route table the DRG attachment is using.
 
   For information about why you would associate a route table with a DRG attachment, see: