Ask HN: How begin contributing to RISC-V?

Unsure if I my prior experience is directly relevant: most of my work has been in scientific computing and graphics, though I've dabbled in a lot of other things.

But I'm posing a pretty open question: how can someone begin contributing to RISC-V? (compilers, toolchains, documentation, testing, etc)

EDIT: There's this article, but its over 2 years old: https://www.sifive.com/blog/all-aboard-part-10-how-to-contribute-to-the-risc-v-software-ecosystem