Vertex Built-ins section in the Spatial Shaders documentation seems outdated

[lucho1]

Your Godot version: 4.0.3

URL to the documentation page: https://docs.godotengine.org/en/stable/tutorials/shaders/shader_reference/spatial_shader.html#vertex-built-ins

Issue description: The Vertex Built-ins section in the Spatial Shaders documentation seems outdated at some points.

I was trying to use WORLD_NORMAL_MATRIX as it says in the doc linked, but apparently it was changed to MODEL_NORMAL_MATRIX in this PR. In there, they flagged out the need of updating the documentation and apparently they did it in this other PR, but it still looks outdated (at least for the built-in variable I tried to use, I didn't checked anything else).

In the PR where they changed the naming of those variables (the 1st I linked), someone flagged that the PR updating the related documentation (the 2nd I linked) only updated the fragment shader part of the docus but not the vertex one.

I'm creating this issue just to flag this :)