Update README.md - [+] Add Cryptool

[loneicewolf]

Hi!

I wanted to add the Cryptool to this (very amazing) repo. Which is why I open this PR.

• Cryptool - A set of tools to help with cryptography. Includes different tools for Cryptanalysis, both locally and via an website.

• Have I followed the CONTRIBUTING.md to the best of my ability? Yes.

• Do I think it is useful for not only me but for everyone using the repo? Yes.

Have a great day! Don't hesitate to reach out if something's wrong.

[loneicewolf]

note if this one is wrong, tell me that and ill close it. I really like this repo (so thanks for making it!)