Explain how to add and use a QFace-based middleware backend in the Parking App

As we were adding tutorials about using IVI generator (AUTOSUITE-1155, https://doc.qt.io/QtIVI/qtivi-ivicore-qface-tutorial-example.html# ) and developing the Parking App (AUTOSUITE-1114, https://doc.qt.io/Neptune3UI/neptune3ui-neptune3ui-com-pelagicore-parking-example.html#), the final version has been released w/o covering how to add and use a QFace-based backend. The IVI related subtask AUTOSUITE-1129 of AUTOSUITE-1114 delivers docs about other aspects to the IVI generator tutorial, not the parking app. This leaves the use of QFace-based middleware backend in Neptune3 UI apps unexplained. I suggest adding a chapter which either has its own content, or explains how to use the learning from the https://doc.qt.io/QtIVI/qtivi-ivicore-qface-tutorial-example.html# or some other way explaining this aspect to the users