Minimize active content: mermaid diagrams to SVG

Currently, the Mermaid diagram in the veilid-python section is rendered by Javascript running in the browser. This ticket is a "todo" to look into prerendering these diagrams to SVG or such.

This conversion is available: https://github.com/mermaid-js/mermaid-cli specifically cites the ability to do so. I haven't examined how to make it play nicely with what we have.