Add tip for QML validation with qmlscene to safety manual FAQ section

Please add tip for the user to run the qmlscene validation for the QML file before building the safety application.  Please check if the FAQ section is good place for it, or is there some other page that is good for it.

The qmlscene tool is integated into Qt Creator. See the picture for the menu location:

For the command line users, the qmlscene tool can be found from the installation directory, for example: D:\QtQSR1.2\5.15.2\mingw81_64\bin