Update the documentation on publishing to Play Store steps

I've recently made a blog post on steps and things to do when publishing a Qt for Android app to the Play Store with Qt 6.9 and CMake. The information detailed there is not yet in the official docs https://doc.qt.io/qt-6/android-publishing-to-googleplay.html. Also that page was needing an update even without the blog post, so now it's time for that.

The blog post is under https://www.qt.io/blog/prepare-a-qt-app-for-play-store-publishing.