updating DIRECTORY.md

Author: github-actions

DIRECTORY.md

@@ -2,6 +2,7 @@
 ## Ciphers
   * [Caesarcipher](https://github.com/TheAlgorithms/Go/blob/master/ciphers/CaesarCipher.go)
   * [Diffiehellmankeyexchange](https://github.com/TheAlgorithms/Go/blob/master/ciphers/diffieHellmanKeyExchange.go)
+  * [Rsacipher(Big)](https://github.com/TheAlgorithms/Go/blob/master/ciphers/RSAcipher(Big).go)
   * [Rsacipher](https://github.com/TheAlgorithms/Go/blob/master/ciphers/RSAcipher.go)
   * [Xorcipher](https://github.com/TheAlgorithms/Go/blob/master/ciphers/xorCipher.go)