This commit does the following:
* Removes Rust development tools from the devenv since all Rust code has been removed
* Removes the deprecated `id` parameter from the `devenv.yml` config, as well as making its formatting actually correct.
* Updates the lockfile of the Nix flake so that all latest versions of tools that are needed are installed.
Also adds a new config example for use with the devenv scripts, as well
as a developer's guide for setting up the Nix environment. This could
also have steps for speific distros, such as what packages to install,
and specific notes.
