text: Title: Document `robot_running` and `dry_run_active` properties of the BuiltIn library in the User Guide
  Body: In issue #4666 we introduced 2 new properties `robot_running` and `dry_run_active` to better support library developers, but these properties were not documented anywhere. 
  
  For RobotCode I regularly get problems that the libdoc cannot be generated (e.g. #d-biehl/robotcode/issues/180) and there are some suggestions for improvement here as well (e.g. #4906)
  
  I think we should introduce a small chapter under chapter 4 in the user manual on this topic, with some examples like here https://github.com/d-biehl/robotcode/issues/180#issuecomment-1816141730