Support for Mermaid JS in Markdown content

[colinbruner]

Support for Mermaid JS in Markdown content

[colinbruner]

**NOTE**: PaperMod does not have any external dependencies fetched from 3rd party
CDN servers. However we do have custom Head/Footer extender templates which you can use
to add those to your website.
https://github.com/adityatelange/hugo-PaperMod/wiki/FAQs#custom-head--footer

I did see this note when opening a PR, I'm going to explore this avenue. I do appreciate the desire not to bake in fetching things from 3rd party CDN servers to the greater theme.

[colinbruner]

Okay, I was able to get this working with the custom footer approach.. although I don't seem to have access to any values in .Page.Store.. will look for a different way of conditionally rendering it as I wouldn't want to pull this script from the CDN on Markdown pages that do not use Mermaid.js

[colinbruner]

It looks like we might need the functionality described in #1356 to more selectively add code under .Content like Mermaid.js