|The following is based on Fallout 76 removed content.|
The note could be found at ATLAS Observatory, overlooking Monongah. To find it, one would up the wooden staircases that lead to the dome, but head straight north. The note would be on a railing, at a platform in between two metal staircases. It was removed with the Steel Dawn update.
NOTE TO SELF:
They put railings on high places for a reason, Dorsey. Almost fell slipping on a wet patch after the rain.
Goes to the back of the queue, though. I don't expect to be working up here too much, and there's more critical stuff to do.