DocumenterMermaid

A Documenter plugin package allows for the inclusion of mermaid.js diagrams in HTML documents:

The above diagram can be included by using the standard Mermaid Markdown syntax:

```mermaid
graph TD
    A[mermaid.js] --> B[DocumenterMermaid]
    B --> C[Documenter]
```

To enable the package, simply load it in the make.jl script. Any code blocks tagged as mermaid will be rendered as diagrams in the generated HTML.