The Rust bookshelf lists a number of books about the Rust programming language. Most of those books are available in mdBook format and are also available on the web as HTML pages.
I personally like to read books off-line on my Kindle device or even on my phone running the Kindle app.
On this site you'll find a number of Rust-related books in epub format.
The books are copyright their respective authors and are available under their respective licenses.
The epub files were generated using the mdbook-epub crate.
You can download the files from here and then you can send them to your Kindle.