docs: improve liquid-auth README and documentation

[J-rayX]

ℹ Overview

📝 Related Issues

✅ Acceptance:

• [x] Conventional Commits
• [x] yarn test:cov passes

[J-rayX]

This PR resolves issue https://github.com/algorandfoundation/liquid-auth/issues/42 Through:

• Refining the repo README structure
• Revising the docs pages:
  • Little structure and heading updates
  • Fixing links
  • Touching up grammar, explanation, and punctuation of content