Minor tweaks (use dist folder, add watch script, update README)

[joeattardi]

This changes the build so that the index.js and index.mjs are placed in a dist subfolder instead of the project root.

Also makes a minor fix to the README which was still referencing index.html instead of index.svelte.

[akauppi]

It also adds build:watch target.

I like using dist/ (or any subfolder) instead of the root. But not quite understanding the src/index.html vs. src/index.svelte issue.

Furthermore, how come there's a PR open since 3 months, at what seems to be the authoritative repo for Svelte? If there are different tiers, those could be marked in the repo description (e.g. [COMMUNITY] or [UNSUPPORTED]).

[antony]

Closing this as the bulk of the work has been done in another PR. If we want to add the watch script, as mentioned in the other PR, it should be named dev in line with the rest of the sveltejs org's scripts. I think the idea of adding watch is a good one.