Part of "Closures" section of book could be clearer

[ghost]

https://doc.rust-lang.org/book/closures.html#closures-and-their-environment

Right before the "move closures" section, the book doesn't really make it clear that this code would not compile:

let nums = vec![1, 2, 3];

let takes_nums = || nums;

println!("{:?}", nums);

It shows part of the compile error, but it just looks like a non-error message from the compiler.

Consider appending "the error message" to "This gives us".