updated crypto principles to match today's cryptographic standards, and fixed grammatical issues

[pUrGe12]

Summary :

This is a fix for issue #346 which called for a revision of principles of cryptography section to match today's standards. The major changes have been listen in the next section.

Description for the changelog :

I have made the following major changes.

1. Stream cipher examples, RC4 to ChaCha20 (because the RC4 algorithm has many vulnerabilities like biases in the key scheduling algorithm)
2. Updated with TLS version 1.3 being the recommended one
3. Updated with note on DES not being a standard, and added AEAD schemes.
4. Corrected spelling errors and other grammatical issues
5. Added link to the cryptographic storage cheat sheet.

Other info :

[jgadsden]

Hello @pUrGe12 , thank you for these changes but they should be done to draft, not release, files

[pUrGe12]

Ahh, sure. I shall open a different pull request then.