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}`.
I generally prefer a more semantic approach. Said another way, it seems odd to me to call an link to NPM as "code" just because we want to style it the same as code. An NPM link is a) a link, b) to an external site, c) which goes to the NPM site, and d) which is talking about an NPM module. For our styling needs, really (d) is driving the style I think.