How to customize pagedown templates

[emilyriederer]

As a potential topic for v2, I remembered this nice guide that @RLesur wrote about creating templates for {pagedown}. This in and of itself it perhaps too broad of a topic to be a "recipe" but we could perhaps draw a few specific ideas from it or show a simple example (e.g. perhaps "deconstructing" how one of the templates like the resume template "works".)

Of course, this is closely related to the topic of Pandoc templates which is already discussed at length.

This was partially inspired by this up-and-coming package mentioned on Twitter