Overhaul and improve readability of the readme

[johannschopplich]

What Is This?

This PR enhances the README's readability:

• Use <details> element to hide responses, which shortens the whole document.
• Replace axios with ohmyfetch
  • It is pretty outdated and bulky by not using the Fetch standard. ohmyfetch is a thin wrapper around fetch and the basis for all requests in Nuxt 3. Thus, not one of the many fetch-wrapping libraries, but a well-tested one. It works in the browser and node.
• It is time to drop CJS in favor of ESM.
• Prettier is used to format the JS and JSON snippets.

👉 Preview of the improved README

<details> Response Example

🆗 Response

{
  code: 200,
  result: "Kirby Starterkit",
  status: "ok"
}

Other Notes

This also closes https://github.com/getkirby/kql/issues/34.

[johannschopplich]

@bastianallgeier Any chance reviewing (and eventually merging) this and releasing v1.1.0 soon? 🙂