List markdown headings with CocOutline [feature request]

[Galicarnax]

For programming languages, CocOutline provides the list of functions, methods, etc. It would be nice if for markdown it provided list of headings (at least top-level), so that it would be possible to quickly jump to certain sections within a document. As far as I know, this is how it works for markdown in some other text editors (e.g., Sublime Text).