updating DIRECTORY.md

Author: github-actions

DIRECTORY.md

@@ -4,8 +4,8 @@
   * Math
     * [Absmaxtests](https://github.com/TheAlgorithms/F-Sharp/blob/main/Algorithms.Tests/Math/AbsMaxTests.fs)
     * [Absmintests](https://github.com/TheAlgorithms/F-Sharp/blob/main/Algorithms.Tests/Math/AbsMinTests.fs)
-    * [Averagetests](https://github.com/TheAlgorithms/F-Sharp/blob/main/Algorithms.Tests/Math/AverageTests.fs)
     * [Abstests](https://github.com/TheAlgorithms/F-Sharp/blob/main/Algorithms.Tests/Math/AbsTests.fs)
+    * [Averagetests](https://github.com/TheAlgorithms/F-Sharp/blob/main/Algorithms.Tests/Math/AverageTests.fs)
     * [Factorialtests](https://github.com/TheAlgorithms/F-Sharp/blob/main/Algorithms.Tests/Math/FactorialTests.fs)
     * [Perfectnumberstests](https://github.com/TheAlgorithms/F-Sharp/blob/main/Algorithms.Tests/Math/PerfectNumbersTests.fs)
     * [Powertests](https://github.com/TheAlgorithms/F-Sharp/blob/main/Algorithms.Tests/Math/PowerTests.fs)
@@ -41,6 +41,7 @@
     * [Abs](https://github.com/TheAlgorithms/F-Sharp/blob/main/Algorithms/Math/Abs.fs)
     * [Absmax](https://github.com/TheAlgorithms/F-Sharp/blob/main/Algorithms/Math/AbsMax.fs)
     * [Absmin](https://github.com/TheAlgorithms/F-Sharp/blob/main/Algorithms/Math/AbsMin.fs)
+    * [Average](https://github.com/TheAlgorithms/F-Sharp/blob/main/Algorithms/Math/Average.fs)
     * [Factorial](https://github.com/TheAlgorithms/F-Sharp/blob/main/Algorithms/Math/Factorial.fs)
     * [Fibonacci](https://github.com/TheAlgorithms/F-Sharp/blob/main/Algorithms/Math/Fibonacci.fs)
     * [Greatest Common Divisor](https://github.com/TheAlgorithms/F-Sharp/blob/main/Algorithms/Math/Greatest_Common_Divisor.fs)