Added Autokey cipher information

README.md

@@ -1,4 +1,4 @@
-# Ciphers
+#Ciphers
 A program to help with some simple ciphers
 This program is designed to allow you to play with some simple ciphers, like the Caesar Cipher.
 Because of how simple these ciphers are they will likely not be of any use if you actually want to keep your data safe
@@ -12,6 +12,11 @@ This cipher is more complicated than a simple Caesar cipher.
 It uses an array of Caesar ciphers and cycles between them based on a key.
 This makes it more secure, but if you are not carful in your message or have a short key it will still output recognizable paterns that can be easily broken.
 
+#Autokey Cipher
+The Autokey cipher is very similar to the Vigenere cipher, but with a more secure key.
+Instead of having a repeated key, the key is used one time and the message itself is used as the rest of the key, out to the length of the message.
+This makes it more secure, but also slower to decrypt.
+
 #Atbash Cipher
 The Atbash cipher is a simple cipher that basically reverses the alphabet.
 A=Z, B=Y, etc.