updating DIRECTORY.md

Author: github-actions

Diff for: DIRECTORY.md

@@ -577,6 +577,7 @@
   * [Hexagonal Number](maths/hexagonal_number.py)
   * [Integration By Simpson Approx](maths/integration_by_simpson_approx.py)
   * [Is Ip V4 Address Valid](maths/is_ip_v4_address_valid.py)
+  * [Is Palindrome](maths/is_palindrome.py)
   * [Is Square Free](maths/is_square_free.py)
   * [Jaccard Similarity](maths/jaccard_similarity.py)
   * [Juggler Sequence](maths/juggler_sequence.py)
@@ -1154,7 +1155,6 @@
   * [Indian Phone Validator](strings/indian_phone_validator.py)
   * [Is Contains Unique Chars](strings/is_contains_unique_chars.py)
   * [Is Isogram](strings/is_isogram.py)
-  * [Is Palindrome](strings/is_palindrome.py)
   * [Is Pangram](strings/is_pangram.py)
   * [Is Spain National Id](strings/is_spain_national_id.py)
   * [Is Srilankan Phone Number](strings/is_srilankan_phone_number.py)