Include the library in the page just after the script tag referencing Vue:
<!-- Include the library in the page -->
<script src="https://unpkg.com/vue/dist/vue.js"></script>
<!-- Add the marked library: -->
<script src="https://unpkg.com/marked"></script>
marked is very easy to use--just call it with the markdown text, and it will return the corresponding HTML.
Try the library with some markdown text:
const html = marked('**Bold** *Italic* [link] (http://vuejs.org/)')
console.log(html)
You should have the following output in the browser console: