Follow contribution guidelines

Author: bomenderick

DIRECTORY.md

@@ -64,6 +64,7 @@
     * [Graph](https://github.com/TheAlgorithms/Rust/blob/master/src/data_structures/graph.rs)
     * [Hash Table](https://github.com/TheAlgorithms/Rust/blob/master/src/data_structures/hash_table.rs)
     * [Heap](https://github.com/TheAlgorithms/Rust/blob/master/src/data_structures/heap.rs)
+    * [KD Tree](https://github.com/TheAlgorithms/Rust/blob/master/src/data_structures/kd_tree.rs)
     * [Lazy Segment Tree](https://github.com/TheAlgorithms/Rust/blob/master/src/data_structures/lazy_segment_tree.rs)
     * [Linked List](https://github.com/TheAlgorithms/Rust/blob/master/src/data_structures/linked_list.rs)
     * Probabilistic