Enable Just the Docs dark color scheme

[KeenanLukeOM]

Found in customization: https://pmarsceill.github.io/just-the-docs/docs/customization/

Just the Docs supports two color schemes: light (default), and dark.

To enable a color scheme, set the color_scheme parameter in your site’s _config.yml file:

Attempt to enable this in our document book. If there is no initial issues with this, we should run with it. Otherwise, ignore this issue and close it.

[Mi-Lan]

@KeenanLukeOM Good suggestion! Where should we put the button for switching?

[KeenanLukeOM]

If a button makes sense, it would likely be above or replacing "This site uses Just the Docs, a documentation theme for Jekyll.". This could be tricky to implement.

I do think that the docs styling could stay consistently in darkmode without an option to switch without any issue though.

[KeenanLukeOM]

As mentioned today, let's attempt to implement a dark mode toggle in place of "This site uses Just the Docs, a documentation theme for Jekyll."