updating DIRECTORY.md

Author: github-actions

DIRECTORY.md

@@ -521,6 +521,7 @@
   * [Naive String Search](https://github.com/TheAlgorithms/Python/blob/master/strings/naive_string_search.py)
   * [Rabin Karp](https://github.com/TheAlgorithms/Python/blob/master/strings/rabin_karp.py)
   * [Remove Duplicate](https://github.com/TheAlgorithms/Python/blob/master/strings/remove_duplicate.py)
+  * [Word Occurence](https://github.com/TheAlgorithms/Python/blob/master/strings/word_occurence.py)
 
 ## Traversals
   * [Binary Tree Traversals](https://github.com/TheAlgorithms/Python/blob/master/traversals/binary_tree_traversals.py)