This gives a decent overview of some of the areas where the focus of Zig is different than Rust. Other than that...I'd just start by reading through the standard library code and the repo to get a feel. It's very very similar to C so you will be immediately comfortable, just cleans up some stuff like removing default global allocator (you pick your malloc basically), better macros (comptime), and encouraging use of non-null terminated strings and fat pointers etc.
https://ziglang.org/learn/why_zig_rust_d_cpp/