Documentation for Custom Add-ons

Is there somewhere I can find documentation for writing a custom Add-On? I have a large team that works on over 50 different Wordpress sites and we have a need for Local by Flywheel to do a few things that I’m wondering if I could accomplish with an Add-on. Thanks!

I haven’t found any documentation except reading the source code for the add-ons in the faq.

I you can wait, Luca Tumedei is writing a tutorial; Developing a Local addon