There was a flight sim for the Mac (F/A 18, I think) that I played in the mid-90's that came with a thick paperback book. It included all the different flight envelopes and even a primer on the concept of "lift" and how it keeps planes in the air.
The manual included with Microsoft Flight Simulator (4.0 maybe?) in the early 90’s was thick and dense. I remember using it to learn how to navigate using VOR stations. They don’t make them like they used to.