I used to leave pull request descriptions empty. "Let the code speak for itself" or "let the commits speak for themselves" are the perfect getaway from the extra work of documenting your thought process.
Recently, I've experienced that spending time on a good description is a worthwhile investment.
Backlinks, or bi-directional liks, are becoming table-stakes for productivity apps since they've been popularized by Roam. It's a simple concept: when you create a link from page A to page B, page B will also reference page A. With traditional hyperlinks, page B wouldn't know about page A unless you explicitly link it back.
Backlinks allow a graph of knowledge to grow organically. When you create a doc for Orders, and mention Products, a Products page will be created or updated with a backlink. Even when not actively documenting Products, readers can get an idea of what they entail because of the linked references.