Make indicator for peer-reviewed lesson

[zkamvar]

This is an extension of #20, where I laid out symbols that we could use for lesson status. Again, from searching feather symbols for "check", we could use user-check to indicate peer-reviewed status and use the doi: <URI> config key to add the badge

The inclusion of the Lab version above reminds me that we will need something like these status indicators to make lessons stand out that have passed peer review (see the banner on https://carpentries-lab.github.io/python-aos-lesson/ for an example of what I mean) but that can definitely be an issue for another day. it will need to link to the relevant Zenodo entry or journal publication.

Originally posted by @tobyhodges in #39 (comment)