Create a GitHub Pages / Blogdown / Hugo documentation site for the containers

Right now, the documentation is in a single (very large) Markdown file, albeit with a table of contents. This needs to be restructured into a documentation site. Given that RStudio is available, the simplest way to build this is with the RStudio "blogdown" package using a Hugo documentation theme. See https://bookdown.org/yihui/blogdown/ and https://themes.gohugo.io/hugo-theme-learn/.