Rename math/add.py to maths/add.py (TheAlgorithms#1857)

* Rename math/add.py to maths/add.py

* fixup! Format Python code with psf/black push

* Fix sum to add

* updating DIRECTORY.md

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: John Law <johnlaw.po@gmail.com>

Author: 3 people

DIRECTORY.md

@@ -107,6 +107,7 @@
     * [Doubly Linked List](https://github.com/TheAlgorithms/Python/blob/master/data_structures/linked_list/doubly_linked_list.py)
     * [From Sequence](https://github.com/TheAlgorithms/Python/blob/master/data_structures/linked_list/from_sequence.py)
     * [Is Palindrome](https://github.com/TheAlgorithms/Python/blob/master/data_structures/linked_list/is_palindrome.py)
+    * [Middle Element Of Linked List](https://github.com/TheAlgorithms/Python/blob/master/data_structures/linked_list/middle_element_of_linked_list.py)
     * [Print Reverse](https://github.com/TheAlgorithms/Python/blob/master/data_structures/linked_list/print_reverse.py)
     * [Singly Linked List](https://github.com/TheAlgorithms/Python/blob/master/data_structures/linked_list/singly_linked_list.py)
     * [Skip List](https://github.com/TheAlgorithms/Python/blob/master/data_structures/linked_list/skip_list.py)
@@ -271,6 +272,7 @@
   * [Abs](https://github.com/TheAlgorithms/Python/blob/master/maths/abs.py)
   * [Abs Max](https://github.com/TheAlgorithms/Python/blob/master/maths/abs_max.py)
   * [Abs Min](https://github.com/TheAlgorithms/Python/blob/master/maths/abs_min.py)
+  * [Add](https://github.com/TheAlgorithms/Python/blob/master/maths/add.py)
   * [Allocation Number](https://github.com/TheAlgorithms/Python/blob/master/maths/allocation_number.py)
   * [Area Under Curve](https://github.com/TheAlgorithms/Python/blob/master/maths/area_under_curve.py)
   * [Armstrong Numbers](https://github.com/TheAlgorithms/Python/blob/master/maths/armstrong_numbers.py)

math/add.py renamed to maths/add.py

@@ -1,6 +1,8 @@
 """
 Just to check
 """
+
+
 def add(a, b):
     """
     >>> add(2, 2)
@@ -14,4 +16,4 @@ def add(a, b):
 if __name__ == "__main__":
     a = 5
     b = 6
-    print(f"The sum of {a} + {b} is {sum(a, b)}")
+    print(f"The sum of {a} + {b} is {add(a, b)}")