* Update using_multiple_threads.rst
Update using_multiple_threads.rst
Adding C++ demos. It doesn't mirror the GDScript exactly, as I found this to be a clearer example of what the thread was doing when testing with multiple threads. All credit to "coder" from this Godot Forum thread: https://forum.godotengine.org/t/gdextension-c-async/36756/7?u=i-snyder
With applied suggestions from AThousandShips code review (many thanks!!)
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Co-authored-by: A Thousand Ships <96648715+AThousandShips@users.noreply.github.com>