Automatically choice file in CDN: jsdelivr, unpkg

[finagin]

With this changes you can use CDN like:

<script src="https://cdn.jsdelivr.net/npm/vue-markdown@2.2.4"></script>

Now you must add path to file like:

<script src="https://cdn.jsdelivr.net/npm/vue-markdown@2.2.4/dist/vue-markdown.min.js"></script>