O’Reilly author here. Seems the author stumbled over pitching them the book. You can almost certainly start with an email. Our initial contact with O’Reilly was only an email. We filled out a small form later with the details of the proposal, but it was not laborious. I can also attest that their tooling is great. From any git commit I can generate a full version of the book in any of its supported formats. I wrote all of my part of the book in vim.