Changes:

Adds this example to the docs for buildFilterShader showing the simplest use of the built-in noise() function to generate an animated texture.

This is correctly positioned into the progression, after the intro of:

• generating colour by coordinate, and
• animation by time uniform

(The PR also corrects a link in the docs from baseFilterShader to buildFilterShader)

• npm run lint passes
• [Inline reference] is included / updated
• npx documentation lint src/webgl/material.js (it doesn't complain about the new code...)