message: Improve comments about reading manifests
diff: # Crate containing the `fathom` binary
  crateName = "fathom";
  - # TODO: find the manifest for ${crateName} in the workspace
  - # minimumRustVersion = (builtins.fromTOML (builtins.readFile ./Cargo.toml)).package.rust-version;
  minimumRustVersion = "1.56.0";
  + # TODO: detect the above variables dynamically using the `Cargo.toml` file.
  + # NOTE: using a workspace complicates this
  +
  + # manifest = builtins.fromTOML (builtins.readFile ./Cargo.toml);
  + #
  + # crateName = manifest.package.name;
  + # minimumRustVersion = manifest.package.rust-version;
  +
  # Setup Rust toolchains to build and test against
  rust = {
  nightly = pkgs.rust-bin.nightly.latest.minimal;
  