Integral vs Integer

Towards the top of the image, one of the footnotes associates `int` with `integral`, which is incorrect when talking about the primitive datatype. See [Rust By Example](https://doc.rust-lang.org/rust-by-example/primitives.html#scalar-types) for instance.

![image](https://user-images.githubusercontent.com/32944537/125801069-e976713d-b702-4d6e-9429-865a4e988338.png)
