QKeyEvent: revise documentation

QKeyEvent documentation has several mysterious sections, some excerpts:

"A value of either 0 or Qt::Key_unknown means that the event is not the result of a known key; for example, it may be the result of a compose sequence, a keyboard macro, or due to key event compression."

what is a keyboard macro?
key event compression?

It does not document that QKeyEvent::key() often returns a unicode value.

"Note that if the event is a multiple-key compressed event that is partly due to auto-repeat, this function could return either true or false indeterminately."

what is that about?

The docs should also include an example of auto-repeat key sequence (there have been several instances when expected behavior is not obvious to API users):

key: press autorepeat: false
key: release autorepeat: true
key: press autorepeat: true
key: release autorepeat: false

With an example where this is useful:

Keys.onReleased: {
    if (!event.isAutoRepeat)
        console.log("key was physically released ") 
}