electron: Fix node generator command

docs/electron.rst

@@ -229,7 +229,7 @@ file contains information about the packages that an application depends on, and
 can be generated by running ``npm install --package-lock-only`` from an
 application's root directory. The script is then run as follows::
 
-  $ python3 flatpak-node-generator.py npm --xdg-layout package-lock.json
+  $ flatpak-node-generator npm package-lock.json
 
 This generates the manifest JSON needed to build the NPM/Yarn
 packages for the application, which are outputted to a file called