https://github.com/markdown-it/markdown-it
API:
https://markdown-it.github.io/markdown-it/
https://github.com/markdown-it/markdown-it/blob/master/docs/development.md
https://github.com/markdown-it/markdown-it/blob/master/docs/architecture.md
https://github.com/nagaozen/markdown-it-toc-done-right

To publish:
https://marketplace.visualstudio.com/manage/publishers/sakryukov