docs: overhaul README

[davidjgoss]

🤔 What's changed?

Overhaul of the README. For convenience, view it here: https://github.com/cucumber/cucumber-js/tree/revamped-readme

Specifically:

• Simple logo, title and tagline
• Add a badge showing latest version on npm
• Remove the dependencies badge which didn't work
• Add a basic "get started" example
• Condense and refactor various parts so users get to the "get started" quicker
• Make some of the documentation links a bit more helpful
• Move links to older versions docs to a separate file

Also links to a new demo using CodeSandbox, since the old-browser demo doesn't reflect the current version and can't be reimplemented with it.

⚡️ What's your motivation?

See cucumber/common#1521 (comment). More informative and welcoming to new users.

🏷️ What kind of change is this?

• 🏦 Refactoring/debt (improvement to code design or tooling without changing behaviour)

📋 Checklist:

• I agree to respect and uphold the Cucumber Community Code of Conduct
• I've changed the behaviour of the code
  • I have added/updated tests to cover my changes.
• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
• Users should know about my change
  • I have added an entry to the "Unreleased" section of the CHANGELOG, linking to this pull request.

[coveralls]

Coverage remained the same at 98.266% when pulling f97f3ed on revamped-readme into 7326ae5 on main.

[aurelien-reeves]

Love it 🤩😍