Animating Thousands of Fish - skipping key material shader setup steps

**Your Godot version:** v4.0.beta6 Official

**Issue description:** The tutorial skips many difficult steps so it can't easily be followed.

1. Finding and downloading the model (simple)
2. Setting up the vertex shader (complicated)

The fish model has 3 different materials. It's isn't obvious how to set up a Vertex shader from scratch where the fish can look like its supposed to as in the tutorial.

**URL to the documentation page (if already existing):**
https://docs.godotengine.org/en/latest/tutorials/performance/vertex_animation/animating_thousands_of_fish.html