create wrapper script for k8s module generation

CONTRIBUTING.md

@@ -31,10 +31,9 @@ To support a new Kubernetes version:
   }
   ```
 
-- Build and copy the updated specs to [`modules/generated/`](./modules/generated/)
+- Build and copy the updated specs to [`modules/generated/`](./modules/generated/) with
 
-      nix build '.#generate-k8s'
-      cp ./result/* modules/generated/
+      nix run '.#generate'
 
 ## Tests
 

flake.nix

@@ -99,6 +99,19 @@
 
         formatter = pkgs.treefmt;
 
+        apps = {
+          generate = inputs.flake-utils.lib.mkApp {
+            drv = pkgs.writeShellScriptBin "gen-modules" ''
+              set -eo pipefail
+
+              nix build '.#generate-k8s'
+              cp ./result/* ./modules/generated/
+
+              rm result
+            '';
+          };
+        };
+
         packages =
           inputs.flake-utils.lib.flattenTree
           {