solved scramble added a caesarDecode challange

[J4unty]

solved scramble and added a caesarDecode challange

Closes #657

Closes #theRelatedIssueNumber

• [x] Running yarn lint does not trigger any linter errors
• [x] The test of the method you have fixed is passing
• [x] You have written a new skeleton method for someone else to work on!
• [x] You have written tests to accompany your skeleton method

[J4unty]

Okay 👍