Add rendering of module cheatsheets to make-live workflow

[jaclyn-taroni]

Related to #521 and discussed this with (at?) @sjspielman in Slack.

I think we could add rendering of module cheatsheets at the same time we render/make live all of the notebooks for a training. My general approach would be to:

• Add a shell script that uses pandoc for the conversion (e.g., scripts/render-cheatsheets.sh). We should be able to do this in the same container as everything else because that container needs to knit things = Pandoc should necessarily be installed.
• Add that step to make live between rendering notebooks and before creating a pull request.