Documentation should mention troubleshooting of b2qt boot

Documentation https://doc.qt.io/QtForDeviceCreation/qtee-troubleshooting.html should mention, that if Boot2Qt is set to boot from the application and the application is not booting, then login in through ssh and running "systemctl status qtlauncher" and
"systemctl status b2qt" will print logs, which may help the find out the problem.