Add Example of Svelte usage (example + lib included)

[SaintPepsi]

I wanted to learn SpacetimeDB, then see if I could implement it in SvelteKit, to which I produced an example project based of the Unreal Example as well as an npm package:

Example Project: https://github.com/SaintPepsi/spacetime-game Package: https://github.com/SaintPepsi/spacetimedb-runes

Not sure what the process is for incorporating this into docs or tutorials but I thought i'd at least post it here to start with.