I hear that. bbPress is missing a lot of the documentation and help that WordPress has. Fortunately, bbPress plugins really are a lot like WordPress plugins. They make use of actions and filters just like WordPress does. The assumption is that you’ll read all about WordPress plugins and then know how to write plugins for bbPress.
You can read all about WordPress plugins and actions and filters at codex.wordpress.org/plugins although this is the page you really want to go to:
https://codex.wordpress.org/Plugin_Resources
You can grep around in the bbPress files to see what actions and filters are available. If you don’t want that much work though go here:
http://www.mittineague.com/dev/bbpaf1_0.php
This site listing all of the bbPress functions is also invaluable:
http://phpxref.ftwr.co.uk/bbpress/nav.html?_functions/index.html