relevant documentation added (TheAlgorithms#1725)

Author: tania-cmyk

ciphers/transposition_cipher.py

@@ -1,6 +1,11 @@
 import math
 
-
+'''
+In cryptography, the TRANSPOSITION cipher is a method of encryption where the
+positions of plaintext are shifted a certain number(determined by the key) that
+follows a regular system that results in the permuted text, known as the encrypted
+text. The type of transposition cipher demonstrated under is the ROUTE cipher.
+'''
 def main():
     message = input("Enter message: ")
     key = int(input("Enter key [2-%s]: " % (len(message) - 1)))