I'm also not a lawyer, but my thought process is like this: in the open source spirit, given this is not a book to be profited from, and profiting from technica

I'm also not a lawyer, but my thought process is like this: in the open source spirit, given this is not a book to be profited from, and profiting from technical books is very hard anyway, developers of some software could contribute technical content which then instead of compensation would only get editor time and in return be allowed to be included in the project's documentation. Real World Haskell, Real World OCaml somehow managed to convince the publisher this is fine. Again, IANAL, just thinking out loud.