parse yaml markdown and interpret tags

[cscheid]

This fixes the following problem:

---
resources: 
  - file*.qmd
---

In Pandoc, that asterisk is just an asterisk because the attempt to parse an emphasis fails, and Pandoc falls back to adding "*". That's not how QMD will work. We want syntax errors. But then, how do you we support glob syntax in an ergonomic way?

This PR has a solution, and the docs explain.