Reworked documentation

[reichhartd]

A few days ago Docusaurus v2 was released.
I find this a good occasion to migrate and extend the website to Docusaurus.

Advantages of this would be:

• Less maintenance effort. Many components are provided by Docusaurus out of the box, and some of the current custom components would not be needed anymore.
• The current design is very similar to the default Docusaurus template, so the design changes would not be that large.
• The documentation would be easier to understand with new components like tabs.
• There are plugins like the Algolia search or an integration for Google Analytics.
• By making the documentation simpler, it would invite new contributors to customize or extend it.

Also I would extend the documentation with some markdown pages, or at least placeholders for follow up pull requests, what I have learned so far about Orval from my own experience or from the examples, like #515.

The new documentation could then be released with the next major version.

[anymaniax]

Hey @reichhartd would be super cool to have a new version for the website. You would try to do it? Or you want me to take a look to it?

[reichhartd]

If you want to, you are welcome to take over the task.

[anymaniax]

it will really depend on the time that I can assign to it