BuddyPress.org

https://codex.buddypress.org/developer-docs/custom-buddypress-loops/

Also, explore around the developer docs site.

Since this is an open source project, there is no one person responsible for documenting BuddyPress. Or put it another way, the community is responsible. It only gets done when someone takes the time and adds to the codex–but, the codex is growing each week. So, you can add to it as well!