Add a diagram showing how rotation works in 2D

**Your Godot version:**
4.4 (doesn't matter in this case)

**Issue description:**
Hi, so the docs say

> Fun fact: In addition to Y being down in Godot, rotation is represented clockwise. This means that all the math and trig functions behave the same as a Y-is-up CCW system, since these differences "cancel out". You can think of rotations in both systems being "from X to Y".

However there is no image on the page that visualizes this. I think there should be an image that visualizes this, like this:


Except that it matches the other images and wasn't made in MS Paint.

**URL to the documentation page (if already existing):**
https://docs.godotengine.org/en/stable/tutorials/math/matrices_and_transforms.html