Shader Master Resource List
The Book of Shaders (https://thebookofshaders.com/) (thanks to Phoenix for this link)
A Beginner's Guide to Coding Shaders (Part 1 (https://gamedevelopment.tutsplus.com/tutorials/a-beginners-guide-to-coding-graphics-shaders--cms-23313), Part 2 (https://gamedevelopment.tutsplus.com/tutorials/a-beginners-guide-to-coding-graphics-shaders-part-2--cms-24111), Part 3 (https://gamedevelopment.tutsplus.com/tutorials/a-beginners-guide-to-coding-graphics-shaders-part-3--cms-24351))
I'll probably expand the list if I find others. Anyone who's found other tutorials for shaders can post below.