Create an autopreview action for this metrics repo

[lwasser]

Currently, we have a peer review metrics dashboard that runs using mystmd. It would be great if we have a live preview here that would allow us to merge some pr's without a full review locally of the submission.

We have a build setup in most of our other repos that uses circle ci. see the packaging repo for an example.

https://github.com/pyOpenSci/python-package-guide

[lwasser]

update - i have created a circle ci build and it works. However, the preview is missing links to js, css etc so the pages dont render properly.