Problem with "primitives.md"

[raslanove]

The document shows that if no type can be inferred, declarations default to isize and usize. According to this:
https://doc.rust-lang.org/book/first-edition/primitive-types.html#numeric-types
This is not the case. Actually doing this on a 64bit machine:
let _x = 30000000000;
gives "warning: literal out of range for i32" when compiled. However,
let _x: isize = 30000000000;
gives no issues whatsoever.