Minor fixes to hashing/short-input_hashing.md
Fix typo in generating_random_data/README.md
Fix typo in README.md
Minor fixes for installation/README.md

- Fix typo
- Fix Samuel Neves' Twitter account name, make it a link
- Modify a sentence to avoid a naked link
Minor fixes for usage/README.md
Minor fixes for helpers/README.md
Fix typos in secret-key_cryptography/aead.md
Merge pull request #2 from rwg/master

Fixes for typos and grammar/style problems