Incorrect OS.get_cmdline_args() usage example

**Your Godot version:**
4.4.1

**Issue description:**
In the documentation for `OS.get_cmdline_user_args()`, an example usage of `OS.get_cmdline_args()` shows it returning `--fullscreen`. If you try this yourself, godot won't actually return `--fullscreen` or any other inbuilt engine arguments I could find.

It's a little unclear if this is intended behavior: https://github.com/godotengine/godot/issues/92831
If it is, the documentation for `OS.get_cmdline_args()` should also state it explicitly.

**URL to the documentation page:**
https://docs.godotengine.org/en/stable/classes/class_os.html#class-os-method-get-cmdline-user-args