Module Builder now has its own documentation site.
This covers the many options it offers developers for fine-tuning their module code, from dependency injection to plugin inheritance, entity base fields, form elements, permissions, library asset files, and more.
Meanwhile, the latest release of Module Builder adds a feature I've wanted to implement for a very long time: when a new form section is added to add a new component (such as a plugin, hook class, or entity type), the form scrolls up to the new section that's just been added with AJAX. This makes it much clearer to understand what's just been changed, and helps with navigating around Module Builder's forms.