undocumented features

According to #53 , Maps are changed, but this is not documented here:
https://www.totaltypescript.com/ts-reset

Furthermore, they are not documented here:
https://github.com/mattpocock/ts-reset/blob/main/readme.md

I think that all of the features should be explicitly documented in the readme, as pull request authors won't be able to update the website. (?)