Only by chance did I see an example document using the toc: true line in their YAML header options in a Markdown file to be processed by Pandoc. And the Pandoc
It is a rather long list that you can browse by running man pandoc in the command line and navigating to "Variables set by pandoc" section under "TEMPLATES."
The top of the list includes the following among many other options:
Variables set by pandoc
Some variables are set automatically by pandoc. These vary somewhat depending on the
output format, but include metadata fields as well as the following:
title, author, date
allow identification of basic aspects of the document. Included in PDF metadata
through LaTeX and ConTeXt. These can be set through a pandoc title block, which
allows for multiple authors, or through a YAML metadata block:
---
author:
- Aristotle
- Peter Abelard
...
subtitle
document subtitle; also used as subject in PDF metadata
abstract
document summary, included in LaTeX, ConTeXt, AsciiDoc, and Word docx
keywords
list of keywords to be included in HTML, PDF, and AsciiDoc metadata; may be
repeated as for author, above
header-includes
contents specified by -H/--include-in-header (may have multiple values)
toc non-null value if --toc/--table-of-contents was specified
toc-title
title of table of contents (works only with EPUB and docx)
include-before
contents specified by -B/--include-before-body (may have multiple values)
include-after
contents specified by -A/--include-after-body (may have multiple values)
body body of document
```