updating DIRECTORY.md

Author: r-sugawara

DIRECTORY.md

@@ -243,6 +243,15 @@
     * [Min Heap](data_structures/heap/min_heap.py)
     * [Randomized Heap](data_structures/heap/randomized_heap.py)
     * [Skew Heap](data_structures/heap/skew_heap.py)
+  * Kd Tree
+    * [Build Kdtree](data_structures/kd_tree/build_kdtree.py)
+    * Example
+      * [Example Usage](data_structures/kd_tree/example/example_usage.py)
+      * [Hypercube Points](data_structures/kd_tree/example/hypercube_points.py)
+    * [Kd Node](data_structures/kd_tree/kd_node.py)
+    * [Nearest Neighbour Search](data_structures/kd_tree/nearest_neighbour_search.py)
+    * Tests
+      * [Test Kdtree](data_structures/kd_tree/tests/test_kdtree.py)
   * Linked List
     * [Circular Linked List](data_structures/linked_list/circular_linked_list.py)
     * [Deque Doubly](data_structures/linked_list/deque_doubly.py)
@@ -285,12 +294,6 @@
   * Trie
     * [Radix Tree](data_structures/trie/radix_tree.py)
     * [Trie](data_structures/trie/trie.py)
-  * KD Tree
-    * [KD Tree Node](data_structures/kd_tree/kd_node.py)
-    * [Build KD Tree](data_structures/kd_tree/build_kdtree.py)
-    * [Nearest Neighbour Search](data_structures/kd_tree/nearest_neighbour_search.py)
-    * [Hypercibe Points](data_structures/kd_tree/example/hypercube_points.py)
-    * [Example Usage](data_structures/kd_tree/example/example_usage.py)
 
 ## Digital Image Processing
   * [Change Brightness](digital_image_processing/change_brightness.py)