Add versions to the sidebar of the documentation, and when viewing the
deployment on zmk.dev, which tracks `main`, add a banner warning about
possibly prefering the docs for a particular stable release.
Added syntax highlighting for devicetree and kconfig files.
The PrismJS project is not accepting contributions right now as they
work on a version 2 of the library, so the new language files are added
directly here.
Also enabled syntax highlighting for various languages that are used in
the docs but aren't enabled in Docusaurus by default.