Better support for asciidoc?

[bluenote10]

First of all, very beautiful theme, thanks for making it!

I recently discovered that the theme doesn't work that well for asciidoc files. At first I thought the problem might be caused by the AsciiDocter extension. However, I now noticed that the tokenization actually works, and it is the theme that is "lacking color", see screenshots+details in asciidoctor/asciidoctor-vscode#393.

Would it be difficult to enable the theme for asciidoc files in a more meaningful way (e.g. using red for headings as the theme does for Markdown)?