Outdated Visual shader documentation/tutorial

**Your Godot version:**
4.1beta3

**Issue description:**
The tutorial/documentation page for the visual shader functionality has not been updated for 4.x even though the page is marked as up to date. The screenshots are all outdated, and some of the information may need to be rewritten.

The page contains a couple of node descriptions, but these seem to be picked quite arbitrarily, with no direct mention of how to get a better understanding of all the other nodes available. So perhaps a good idea would be to include a link to the class reference listing for all the visual shader nodes
https://docs.godotengine.org/en/latest/classes/class_visualshadernode.html
For further information on the individual nodes.

**URL to the documentation page:**
https://docs.godotengine.org/en/latest/tutorials/shaders/visual_shaders.html