Add adaptive difficulty sections to documentation

[K-Meech]

Adds sections to the docs explaining how adaptive difficulty works for each mini-game.

While we mention most of these parameters in the Main objects / values to edit during play testing sections, this is brief and mixed with other variables that aren't related to game progression, which makes it hard to get an overview of how this works. I've been making some local notes on this for each game while creating the save data (to help me with testing each game), so I figured it would be useful to integrate this into the main docs.

[thompson318]

Descriptions are clear and match my understanding of the adaptive difficulty for each mini game. Added a minor suggestion for rocket launch. Not sure if it makes things clearer though.

[K-Meech]

Thanks @thompson318 - I added your clarification to the rocket launch section. I'll go ahead and merge this now.