Minor documentation change

[m4nh]

In your Svelte Getting Started guide: https://pdfslick.dev/docs/svelte there is a minor error:

import "@pdfslick/solid/dist/pdf_viewer.css";

Should be:

import '@pdfslick/core/dist/pdf_viewer.css';

Just to avoid Svelte user to download the solid version. Sorry if I'm being a pain in the ass :)