Migrate all documentation to a website

[nojaf]

I propose we have a single place where we host all documentation.
Following other F# projects, it makes sense that we use FsDoc for this.

The existing way of Fantomas deals with this problem is through different markdown files, blogposts and videos spread over multiple platforms.

Premise

The documentation should cover multiple topics and should really be the place to look at for both end-users and contributors. This issue will be used to bundle all the action points, if there are any community suggestions I'd be happy to discuss them here.

Technical

We should have our own theme in FsDocs to have full control of what we are trying to achieve.
Make sure of Bootstrap and Sass (using the Sass style, not the Scss flavour), similar to how the landing page is constructed.

Be inspired by other visually pleasing documentation websites (Arrow is a good example). And respect our new branding guidelines.
Use the correct colours and font (notice that you should use Reem Kufi, that part of the guide needs an update).

Principles

As mentioned on our Discord channel, please visit https://documentation.divio.com/ to capture everything we need on our documentation website.

Work

• Create initial landing page
• End-user documentation #2316
• Optimize mobile experience #2317
• API documentation #2318
• Add Code generation documentation #2319
• Add contributors documentation #2320
• Add documentation for issue reporters #2321
• Add release manager documentation #2322
• Add style guide documentation #2323
• Add general FAQ page #2324
• Host documentation on fantomas.io #2325
• Add suggestions how people can contribute #2329
• List what specific features we use from the F# language #2330

Extra information

Estimated cost (XS, S, M, L, XL, XXL): L / XL

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