updating DIRECTORY.md

Author: github-actions

DIRECTORY.md

@@ -164,6 +164,8 @@
  * [FormatPhoneNumber](https://github.com/TheAlgorithms/Javascript/blob/master/String/FormatPhoneNumber.test.js)
  * [LevenshteinDistance](https://github.com/TheAlgorithms/Javascript/blob/master/String/LevenshteinDistance.js)
  * [LevenshteinDistance](https://github.com/TheAlgorithms/Javascript/blob/master/String/LevenshteinDistance.test.js)
+ * [MaxCharacter](https://github.com/TheAlgorithms/Javascript/blob/master/String/MaxCharacter.js)
+ * [MaxCharacter](https://github.com/TheAlgorithms/Javascript/blob/master/String/MaxCharacter.test.js)
  * [PatternMatching](https://github.com/TheAlgorithms/Javascript/blob/master/String/PatternMatching.js)
  * [PatternMatching](https://github.com/TheAlgorithms/Javascript/blob/master/String/PatternMatching.test.js)
  * [ReverseString](https://github.com/TheAlgorithms/Javascript/blob/master/String/ReverseString.js)