renamed hello template to shell

shell/flake.nix

@@ -0,0 +1,13 @@
+{
+  description = "Template for a devShell";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let pkgs = import nixpkgs { inherit system; };
+      in with pkgs; { devShells.default = mkShell { packages = [ typst ]; }; });
+}