For "Stratospheric - From Zero to Production with Spring Boot and AWS" (https://stratospheric.dev/ ) we used Markua (http://markua.com/ ), Leanpub's Markdown flavour.

We generated the book through Leanpub, so we relied on their typesetting choices entirely.

In terms of the writing process we (three co-authors) used "feature" branches on GitHub and pull requests for each chapter, i.e., once a chapter was considered done, the other two authors reviewed and edited the result.