chore(docs): restructure docs so they can be ingested by svelte.dev

[dominikg]

This moves the docs markdown files into a structure parsable by svelte.dev generator and adds symlinks in the old places so that existing links keep working.

[eltigerchino]

Is it worth thinking about de-duplicating the config option info between this file (and potentially others) and the JSDocs? (generating the docs from the JSDoc types like we do in Svelte and SvelteKit)

[dominikg]

how does that work and can it be added to a pre-commit hook + ci check?

[eltigerchino]

I think you'll have to ask Elliot who made new changes to the svelte.dev bot https://discordapp.com/channels/457912077277855764/1385015784564330589/1409640631160012810

For how it works, there's an example in https://github.com/sveltejs/kit/blob/main/documentation/docs/98-reference/50-configuration.md there seems to be some kind of notation such as > TYPES: Configuration#Config but we probably need to find out from @Rich-Harris and document it somewhere