As I read further, I see the following articles:
https://meta.discourse.org/t/best-way-to-setup-a-private-customised-discourse-repo/21272
This is all pretty heavy weight for what I want to do. I need to apply a patch to highlight.js to introduce 3 extra lines. Can this be done safely from the container/app.yml file (or some other configuration point)? There is a build process for highlight.js and its not clear to me when that takes place in Discourse.