I’m still playing around with the forum’s Mermaid support, over at Mermaid musings: simple graphs of actors. If anyone wants to see some workable ways to use and format Mermaid code, check out the snippets in those postings.
FWIW, I’d still like the forum admins to check into supporting DOT (part of the Graphviz suite). It’s quite a bit like Mermaid, but it allows more complex and interactive diagrams.