Proposal: Improve documentation in several repositories.

[TheAlgorythm]

I've had a few ideas on improving the documentation in several repositories. I can try to implement them but I wanted to make sure that there are no objections against them.

• Add Security/recommended column to
  • password-hashes
  • block-ciphers
  • Proposal: "Recommended" badges #10
• Add salt/info recomendation for KDFs/HKDF [Understanding HKDF, KEMs and Post-Quantum age]
• Add AEAD hint (like MAC) to block-modes as it should be better to use AEAD instead of a self built integrity check because of things like the Doom Principle

(I'm not a cryptographic engineer. Just an IT-Security person with some knowledge in the usage of cryptography)

[TheAlgorythm]

@tarcieri Should I open individual issues in the regarding repos? Or should I directly do PRs?
I just don't want to create five different issues/PRs when they are not wanted.

[tarcieri]

Documentation improvements are welcome. Please open PRs, or if you think the change is large enough to warrant it you can open an issue in advance to discuss