Automated addition of Foundations material to the Gallery

[brian-rose]

As discussed at today's EWG, since we now have the "Resource Gallery" rather than "external" links, it makes sense to include links to our own tutorial material from the Foundations book.

There is interest is setting up some automation for initiating PRs to add links to each Foundations page with appropriate tags. Solving the technical problem of automated search through the content of a JupyterBook would have lots of uses beyond Pythia.

@dopplershift and @kmpaul exchanged a few ideas about this at the meeting. We can discuss here and/or at the next IWG meeting.

[brian-rose]

Maybe we can pick this one back up after #156 is merged and we start adding Pythia content to the gallery.