updating DIRECTORY.md

Author: Ramy-Badr-Ahmed

Diff for: DIRECTORY.md

@@ -291,19 +291,16 @@
     * [Stack With Doubly Linked List](data_structures/stacks/stack_with_doubly_linked_list.py)
     * [Stack With Singly Linked List](data_structures/stacks/stack_with_singly_linked_list.py)
     * [Stock Span Problem](data_structures/stacks/stock_span_problem.py)
+  * Suffix Tree
+    * Example
+      * [Example Usage](data_structures/suffix_tree/example/example_usage.py)
+    * [Suffix Tree](data_structures/suffix_tree/suffix_tree.py)
+    * [Suffix Tree Node](data_structures/suffix_tree/suffix_tree_node.py)
+    * Tests
+      * [Test Suffix Tree](data_structures/suffix_tree/tests/test_suffix_tree.py)
   * 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)
-  * Suffix Tree
-    * [Suffix Tree Node](data_structures/suffix_tree/suffix_tree_node.py)
-    * [Suffix Tree](data_structures/suffix_tree/suffix_tree.py)
-    * [Example Usage](data_structures/suffix_tree/example/example_usage.py)
 
 ## Digital Image Processing
   * [Change Brightness](digital_image_processing/change_brightness.py)