Pandoc V2.10 and Underline support

For anyone that uses Pandoc, just to mention the latest version released a few days ago offers comprehensive underline support. For Scrivener that means we can create an underline style that can compile into an [inline span]{.ul} that Pandoc can then convert to any of the output formats it supports.

github.com/jgm/pandoc/releases/tag/2.10