Is there a great YAML in RMarkdown guide out there?

This came up on Twitter yesterday in a thread on a whole YAML template for academic articles, but, is there a good definitive and straightforward guide to RMarkdown YAML? I ask as once you dive off of the basics, there appear to be a lot of options out there, but little aid in navigating - and students in particular get both excited and confused.


RMarkdown documentation has a lot of content:

But these are by no means complete. For example, I always set my date to the current date.

Also, Yihui Xie presented "Customizing & Extending R Markdown" at rstudio::conf(2017L)