Rustdoc generic array impl doesnt show length

The following code:
```Rust
#![feature(const_generics)]

pub trait Array {
    type Item;
}

impl <T, const N: usize> Array for [T; N] {
    type Item = T;
}
```

produces the following docpage:
https://imge.to/i/vedzx

Obviously the `N` is missing in the specification for what type the trait is implemented.. `for [T; _]`