This one is short but simple since I didn't have it on my last flight and I fly again tomorrow. To access your Rust documentation when you aren't online:
rustup docs --book
That brings up a browser with a full implementation of the rust docs. Not only is there a full table of contents but it is also searchable.
There is also the magic of devdocs.io but that requires that you were wise enough to have pre-clicked the install for offline option. And, alas, I was not.