> I like Org mode, but the syntax highlighting support is not great

I know. That's why I said "I hope Github improves Org mode support at some point." :)

> I have been looking at AsciiDoc

If you like Org mode, you can overcome the Github/etc. Org mode rendering limitations by hosting small static sites for your projects. You may choose to do so by simply exporting Org to HTML using ox-html[1], or even exporting Org to markdown for Hugo (disclaimer: my package -> ox-hugo)[2].

I mean, if you like using Org mode, and Github et al don't see the value in improving support for that, don't use them to render Org mode docs :)

[1]: https://eless.scripter.co/

[2]: https://ox-hugo.scripter.co/