Update documentation how to build iOS projects with cmake

It would be great if the documentation could be updated on how to build Qt applications using cmake.

Currently I found mainly https://doc.qt.io/qt-6/ios.html#building-applications-from-the-command-line that seems to be outdated. It does rely on qmake instead of cmake for the build. Also, contrary to the headline, it does not really say how to build from the command line, but how to build from the XCode GUI. It would be awesome if projects can be built purely from the command line, for continuous integration, like with cmake and ninja?

Originally this question was raised in https://bugreports.qt.io/browse/QTCREATORBUG-23574 but it seems more appropriate here.