"Best practices" and "documentation" are both pretty broad. And there are already resources like the Rust API Guidelines book, which go into incredible detail about how to design libraries. Though maybe we could link to that at the bottom of the intro page as a good resource.
"Logging": I imagine we'll need a whole chapter to describe what's possible/helpful with tracing. I wonder if there's a better place to submit that info, and then link this book to it.
"Comments": Not sure what you mean. There are some best practices associated with comments, e.g. putting a PANIC comment above that looks like it might panic to justify it. Not sure what section that would go in.