[ADDITION] Add an article about Using Save Files

[KoloInDaCrib]

What does this PR add?

This PR provides an article about using Saves, both for accessing the data from the game, as well as writing to and reading from modOptions, which is the main way for the player to create their own custom save fields.

[Kade-github]

Pretty much all of these snippets I realize have the same thing where they don't really lead you anywhere. Adding comments like I did in a few of these comments to all of them would go a nice way I feel.

[KoloInDaCrib]

Pretty much all of these snippets I realize have the same thing where they don't really lead you anywhere. Adding comments like I did in a few of these comments to all of them would go a nice way I feel.

Done in a recent commit. I've also added imports to the 100k score example, since it relied on PlayState.