Knight undoing 

"This is simply meant to illustrate a fork, it isn't intended to show all of the pieces and isn't intended to be a game"

It may have originally been intended only to show that... But there's no reason not to use this situation to show the reader both one of the knight's advantages and one of it's weaknesses. It's really a very good example of that, which by the way the text adjacent to it describes. In fact, as I read the mentioned text, I even expected that picture to show me that. And frankly, it's a better example of that weakness than the picture which shows a black knight, its possible moves, and a cornered knight with only two possible moves. So I suggest either undoing your undoing or perhaps adding a new picture, with the knight cornered after taking the rook there.