Missing description on "Spatial shaders" page for "Fragment built-ins" - "in mat3 MODEL_NORMAL_MATRIX"

[Inkweeper]

Your Godot version:

4.3

Issue description:

The description for the built-in "in mat3 MODEL_NORMAL_MATRIX" in the "Fragment built-ins" part is missing, making its utility obscure.

URL to the documentation page:

https://docs.godotengine.org/en/stable/tutorials/shaders/shader_reference/spatial_shader.html#fragment-built-ins