Document idiomatic way to sort rollback related queries

[JonathanPicques]

I don't know what is the best way to sort queries, so far I've used

fn system(
    mut query: Query<(&Player), With<Rollback>>,
) {
    let mut query = query.iter_mut().collect::<Vec<_>>();
    query.sort_by(|(player_a, ..), (player_b, ..)| player_a.cmp(player_b));
}

This solution is fine, but as opposed to the example below, Player has an handle to perform a stable sort ...

fn system(
    mut query: Query<(&Rollback, &mut Transform, &mut PlatformController)>,
    order: Res<RollbackOrdered>,
) {
    let mut query = query.iter_mut().collect::<Vec<_>>();
    query.sort_by(|(rollback_a, ..), (rollback_b, ..)| {
        order
            .order(**rollback_a)
            .cmp(&order.order(**rollback_b)) // this is ugly :D
    });

    for (_, mut transform, mut controller) in query {
        // do stuff
    }
}

... whereas here, neither Transform nor PlatformController has a stable sort discriminant
This looks like the best approach, but it is not documented nor used in examples, so I might be using it wrong