Documentation improvements for Viewer profiling UI and console

Viewer profiling UI is a great tool for debugging the presentation performance issues. We do have http://doc.qt.io/qt3dstudio/runtime/qt3d-runtime-profileui.html documentation but this document is not linked from: https://doc.qt.io/qt3dstudio/qt3dstudio-viewer.html and for example the console functionality is not covered in the documentation.

Furthermore additional tips & tricks on actually analyzing the presentation content would be valuable. Laszlo's blog post: http://blog.qt.io/blog/2018/06/27/whats-qt-3d-studio-scene/ has already good tips that could be re-used.