The next sections are all optional and are not required to really be productive in Rust. Some of it are alternative resources or extra content to learn from. Others is just miscellaneous content that is not really required to be productive in Rust, but might be interesting to you.
This guide is either way not meant to be read in a single session or series. Take it as yours and just use it as part of your learning journey. Take your time as learning Rust isn't easy, but it is a very rewarding one once you did climb the mountain and are dancing with a double rainbow in the background.