If you want to optimize your learning experience, then learn Go first. Rust has a very steep learning curve, whereas you can pick up Go very very quickly.
I learned Go by reading The Go Programming Language. It's a bit old, but a very good book nonetheless.
I second this. I'm a huge Rust fan, and not really a Go fan, but if you're thinking about leaning both, it will be much faster to learn Go first. Spend a couple weeks on that, and then you'll have another data point to compare while you learn Rust. (Go also distinguishes between pointers and values, which will be a helpful concept to have under your belt when you start Rust.)
I learned Go by reading The Go Programming Language. It's a bit old, but a very good book nonetheless.