Support for Mermaid Graphs

Support for Mermaid Graphs

It would be extremely useful if Nimbus had direct, built-in support for Mermaid graphs - ie., perhaps a 'mermaid' block, where we could type in the graph description and have it automatically rendered by mermaid.

Mermaid graphs are easy for the user to create, are highly customisable, and cover a wide - and ever-growing - range of use-cases.