Latest documentation for plugins singleton missing

**Your Godot version:**
Godot_v3.4.4-stable_mono_win64
**Issue description:**
On the stable version of the docs; everything is covered in both C# and GDScript. However on the latest version; there is a missing
C# example near the bottom regarding singletons. I'd like to see the C# example added please.

**URL to the documentation page (if already existing):**
Stable: https://docs.godotengine.org/en/stable/tutorials/plugins/editor/making_plugins.html
Latest: https://docs.godotengine.org/en/latest/tutorials/plugins/editor/making_plugins.html