Add a crypto challenge: "Broken Decryptor"

[apehex]

Hi :) if you need the passwork ==> apehex

• Write in English --> :heavy_check_mark:
• All the write-ups must be password protected --> :heavy_check_mark:
• Remember in addition to add the write-up to update the Readme file keeping the format --> :heavy_check_mark:
• If you change from category be pretty sure of updating correctly the tables and re-ordering the "ranking" if needed --> :heavy_check_mark: