templates nix flakes

Ajouts des templates pour les flakes.

nix flake init -t nxc#basic

ou

nix flake new -t nxc#basic mon_folder

On pourrait aussi les generer automatiquement à partir du dossier examples mais les descriptions seraient un peu plates ...

let
  getFolders = { path }:
    let dir = builtins.readDir path;
    in builtins.filter
    (name: let type = builtins.getAttr name dir; in type == "directory")
    (builtins.attrNames dir);

  buildSet = { path }:
    let folders = getFolders { inherit path; };
    in builtins.listToAttrs (builtins.map (folder_name: {
      name = "${folder_name}";
      value = {
        path = "${path}/${folder_name}";
        description = "Example for ${folder_name}";
      };
    }) folders);
in buildSet { path = ./examples; }