updating DIRECTORY.md

Author: github-actions

DIRECTORY.md

@@ -186,6 +186,7 @@
  * [SieveOfEratosthenes](https://github.com/TheAlgorithms/Javascript/blob/master/Maths/SieveOfEratosthenes.js)
  * [Softmax](https://github.com/TheAlgorithms/Javascript/blob/master/Maths/Softmax.js)
  * [SquareRoot](https://github.com/TheAlgorithms/Javascript/blob/master/Maths/SquareRoot.js)
+ * [SumOfDigits](https://github.com/TheAlgorithms/Javascript/blob/master/Maths/SumOfDigits.js)
  * test
  * [Abs](https://github.com/TheAlgorithms/Javascript/blob/master/Maths/test/Abs.test.js)
  * [Area](https://github.com/TheAlgorithms/Javascript/blob/master/Maths/test/Area.test.js)
@@ -223,6 +224,7 @@
  * [ReversePolishNotation](https://github.com/TheAlgorithms/Javascript/blob/master/Maths/test/ReversePolishNotation.test.js)
  * [SieveOfEratosthenes](https://github.com/TheAlgorithms/Javascript/blob/master/Maths/test/SieveOfEratosthenes.test.js)
  * [Softmax](https://github.com/TheAlgorithms/Javascript/blob/master/Maths/test/Softmax.test.js)
+ * [SumOfDigits](https://github.com/TheAlgorithms/Javascript/blob/master/Maths/test/SumOfDigits.test.js)
  * [Volume](https://github.com/TheAlgorithms/Javascript/blob/master/Maths/test/Volume.test.js)
  * [Volume](https://github.com/TheAlgorithms/Javascript/blob/master/Maths/Volume.js)
  * [WhileLoopFactorial](https://github.com/TheAlgorithms/Javascript/blob/master/Maths/WhileLoopFactorial.js)