include option to compile a table of contents to a notebook?

[hamilton]

This might be a worthwhile notebook-level option, which takes all of the various header elements and creates a linked table of contents, linked to scroll to the appropriate anchor.

[bcolloran]

https://github.com/Oktavilla/markdown-it-table-of-contents
https://github.com/medfreeman/markdown-it-toc-and-anchor
https://github.com/samchrisinger/markdown-it-toc (repo deleted since comment)
none of these has particularly many stars, but maybe a starting point

https://github.com/jonschlinkert/markdown-toc has ~500 stars. we could try switching from markdown-it to see https://github.com/jonschlinkert/remarkable to use that plugin. but the katex plugin for remarkable has way less stars than the one for markdown-it, and probably quality latex rendering is more important (a less stellar TOC implementation won't make or break us)