Added README and created a directory for the scripts

Author: namrun

Substitution_Cipher/README.md

@@ -0,0 +1,10 @@
+## Substitution Cipher
+
+- The Substitution Cipher is a Cryptographic technique used for the encryption of a message
+- The encryption is done based on a key agreed upon by the sender and receiver of the message
+- The letter is encoded/mapped to a different letter/character
+
+## Working
+
+- The user is prompted to enter the message as well as the key according to which the message will be encrypted
+- The key will be accepted as a CSV file