There's also ongoing work on the (for now hidden) Bevy Book https://bevy.org/learn/book/intro/

Already seems like a great resource to me but it's still WIP.

As someone who is actively working on the Bevy Book, the next engine release should include the first public release of the Bevy Book. And once it's out, then we'll be doing our best to keep it updated and expand it alongside the Bevy engine.