The GNU Boot project started creating a manual (online, pdf) to better organize the documentation about GNU Boot. It also enables to target a wider diversity of users, contributors and maintainers.
Note that the online manual can also be saved locally. In that case it’s a good idea to use the “Save Page As …” function of your browser instead of “Save Link As …” to get the picture(s) as well.
Markdown file for this page: https://gnu.org/software/gnuboot/docs/index.md