message: Added comment with instructions
diff: #include "CoreMinimal.h"
  #include "VehiclePawn.h"
  +/*
  + * To use another physics / flight-management system, comment-out the line below,
  + * write your own Physics::createPhysics() factory method, and surround this method
  + * with #ifndef _USE_HACKFLIGHT ... #endif
  + *
  + */
  #define _USE_HACKFLIGHT
  /**
  