Export component to allow usage without registering as plugin

[moander]

I also added a script setup example using the component.

[moander]

I see now that it is already documented how to do that.. But script setup with that additional export saves you a few lines :-)

<template>
    <highlight-js autodetect code="function() {}" />
</template>

<script setup>
import 'highlight.js/lib/common';
import { HighlightJs } from "@highlightjs/vue-plugin";
</script>