No example of how to use QML_NAMED_ELEMENT in documentation

https://doc-snapshots.qt.io/qt5-5.15/qqmlengine.html#QML_NAMED_ELEMENT has no example of how the macro is actually used. https://doc-snapshots.qt.io/qt5-5.15/qtqml-cppintegration-definetypes.html#registering-an-instantiable-object-type just says:

QML_NAMED_ELEMENT(<name>)

I've already managed to pass in a string when it actually just needs the type name without quotes.

We should have a code snippet for this.