I put book outline in my previous blogpost, put it in the github repo and...
... found out that it was a really bad move. Proposing changes to a book should be deadly easy, and not require anyone to know how to use asciidoc.
So I did a small research today, and found a collaborative book writing service - Penflip. It is simple. It looks nice. It is a service, so why not?
If you wish to help - here is the link which allows for participation - just click it, choose random chapter and put your 2 cents!