I've been doing quite a lot of work with the API of late, and with the recent v12 release, you may not have noticed, but there's a newly updated version of the API spec to go along with it.
A new API spec means a new client build, and so I decided to not only document the update process, but the whole process from end to end - building, using, AND keeping the client up to date.
https://docs.google.com/document/d/e/2PACX-1vRbrhn8xdW2LeDbnDastBp6fH4vhR4gytAZWYa_uZ2m8OmSfgnjtBeBpVUtV3DHIKe_wQFbg8Pk3gLt/pub
Hope this is helpful to someone out there, a LOT of hours of figuring stuff out compressed into a single document. I've tried not to go overboard with explaining every last detail, this is definitely aimed at people who already know their way around Git, Composer, etc., but if there's something you feel it's missing, I'm happy to update it, and any questions, feel free to ask!
