"Add a link to the notebook at the bottom of each tutorial."
function append_notebook_links()
    dir = TUTORIALS_DIR
    md_paths = filter(endswith(".md"), readdir(dir; join=true))
    for md_path in md_paths
        md_file = basename(md_path)
        without_extension, _ = splitext(md_file)
        jl_file = "$(without_extension).jl"
        url = "/notebooks/$jl_file"
        open(md_path, "a") do io
            text = """\n
                _To run this tutorial locally, download [this file]($url) and open it with
                [Pluto.jl](https://plutojl.org)._

                ~~~

                <link rel="stylesheet" href="/libs/highlight/github.min.css">
                <script src="/libs/highlight/highlight.min.js"></script>
                <script>hljs.highlightAll();</script>
                
                ~~~
                """
            write(io, text)
        end
    end
    return nothing
end