Could you add an example (preferably showing the various cases)? e.g.

```rust
use std::iter::OrdIterator;

let v: &[int] = [];
assert_eq!(v.iter().min_max(), NoElements);

let v = [1];
assert_eq!(v.iter().min_max(), OneElement(1));

let v = [1, 1, 1];
assert_eq!(v.iter().min_max(), MinMax(1, 1));

let v = [3, 4, 2, 1];
assert_eq!(v.iter().min_max(), MinMax(1, 4));
```