feat: added crack caesar cipher challenge

Author: micheleriva

challenges/intermediate/crack-caesar-cipher/README.md

@@ -0,0 +1,6 @@
+# Crack the Caesar Cipher
+
+This exercise whats you to crack the Caesar Cipher. <br />
+You can find three test cases inside the `/cases` directory. You should determine the shift factor for each of them.
+
+Recommended method: you can use word frequency to analyze the content and determine the shift factor: [https://en.wikipedia.org/wiki/Letter_frequency](https://en.wikipedia.org/wiki/Letter_frequency).