updating DIRECTORY.md

Author: github-actions

DIRECTORY.md

@@ -15,8 +15,8 @@
   * [Gaussian Elimination](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/computer_oriented_statistical_methods/Gaussian_elimination.cpp)
   * [Newton Raphson Method](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/computer_oriented_statistical_methods/newton_raphson_method.cpp)
   * [Ordinary Least Squares Regressor](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/computer_oriented_statistical_methods/ordinary_least_squares_regressor.cpp)
-  * [Secant Method](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/computer_oriented_statistical_methods/Secant_method.CPP)
-  * [Successive Approximation](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/computer_oriented_statistical_methods/successive_approximation.CPP)
+  * [Secant Method](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/computer_oriented_statistical_methods/secant_method.cpp)
+  * [Successive Approximation](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/computer_oriented_statistical_methods/successive_approximation.cpp)
 
 ## Data Structure
   * [Avltree](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/data_structure/AVLtree.cpp)