add missing mention of sort_unstable_by_key in QuerySortedIter docs (#14108)

# Objective

There is a missing mention of `sort_unstable_by_key` in the
`QuerySortedIter` docs.

## Solution

Add it.

Author: Victoronz

crates/bevy_ecs/src/query/iter.rs

@@ -945,7 +945,7 @@ impl<'w, 's, D: QueryData, F: QueryFilter> Debug for QueryIter<'w, 's, D, F> {
 ///
 /// This struct is created by the [`QueryIter::sort`], [`QueryIter::sort_unstable`],
 /// [`QueryIter::sort_by`], [`QueryIter::sort_unstable_by`], [`QueryIter::sort_by_key`],
-/// and [`QueryIter::sort_by_cached_key`] methods.
+/// [`QueryIter::sort_unstable_by_key`], and [`QueryIter::sort_by_cached_key`] methods.
 pub struct QuerySortedIter<'w, 's, D: QueryData, F: QueryFilter, I>
 where
     I: Iterator<Item = Entity>,