lots of Rust cookbook links pop up after a google search...which one should Rust newbies be using ?
The one produced by the Rust project is at https://rust-lang-nursery.github.io/rust-cookbook/ (and the corresponding repo is at rust-lang-nursery/rust-cookbook).
The reason it's in the rust-lang-nursery organization rather than the rust-lang organization is that there aren't enough maintainers to make it the quality we'd like an "official" resource to have. But everything in there should be accurate, if a little out of date.
Anything else called "Rust cookbook" is likely a completely different resource (or a fork/mirror that's probably even less maintained), and I don't know any of the others well enough to comment on whether someone would find them useful.