Build the HTML presentations with make. Convert the slides to PDF
with make pdf.
Sometimes it's necessary to update the flake inputs, like nixpkgs
or plantuml. The command
nix flake updateupdates all flake inputs, while
nix flake lock --update-input <my-input>may be used to update a single input to its latest version. See the
respective help pages for the specific Nix commands, like nix flake lock --help.