Investigate mermaid plugin

[ptbrowne]

Mermaid is useful to create diagrams and schemas. We already
use it on some of our docs but it is a bit tedious to write
the diagram code in the editor, save the image, move the image
to the git repo, and link it. Additionally, if we forget to
update the image, it can be desynced.

This plugin could help with writing and maintaining easily
mermaid diagrams in our docs by using the mermaid javascript
library to render the diagram from source on the client.

See https://github.com/fralau/mkdocs-mermaid2-plugin#general-principle

What do you think ? Is anybody interested in testing it ?