Add diagramming feature via Mermaid (see Hugo Learn Theme for reference)

[aral]

The Hugo Learn Theme has Mermaid-based diagramming by default. This would be a valuable addition to Cupper and should be relatively easy to port from that theme.

(Also, see the Typora editor app – which also uses Mermaid internally – for a possible front-end for authoring and rapidly prototyping documentation with diagrams in Markdown for Cupper.)

Reference: https://learn.netlify.com/en/ Source: https://github.com/matcornic/hugo-theme-learn

[frastlin]

The problem is that the Mermaid diagrams are not very accessible with a screen reader. The alt text does not give nearly enough information to be useful. It would be better if the code was the alt text, as it's more understandable. The diagrams need some work before they could be considered inclusive for screen reader users.