Fix typo in GroupingMap::minmax docs
@@ -402,7 +402,7 @@ impl<I, K, V> GroupingMap<I>
/// If several elements are equally maximum, the last element is picked.
/// If several elements are equally minimum, the first element is picked.
///
- /// See [.minmax_by()](../trait.Itertools.html#method.minmax) for the non-grouping version.
+ /// See [.minmax()](../trait.Itertools.html#method.minmax) for the non-grouping version.
///
/// Differences from the non grouping version:
/// - It never produces a `MinMaxResult::NoElements`
