beginning of dust integration page

This is just a start, but I think it might be good to get in to start review/discussion.

Still notably TODO is the docs for `{@formatMessage}`.
Use the `{{#code}}` block helper for this, which also allows you to specify and language and it will do the escaping and syntax highlighting for you:

```handlebars
{{#code lang="html"}}
<script src="dustjs-linkedin.js"></script>
{{/code}}
```