Document bindings for compute shader stages

[EtienneParmentier]

There is no documentation about how to bind resources to the compute shader stage, but vertex and fragment/pixel shaders bindings are explained on the wiki page of SDL_CreateGPUShader
I first created an issue on the main repo but figured this repo is more appropriate.

[slouken]

@thatcosmonaut, do you have your article available?

[thatcosmonaut]

https://wiki.libsdl.org/SDL3/SDL_CreateGPUComputePipeline#remarks

[EtienneParmentier]

I got it, compute pipeline are created using a different function entirely, so the bindings are documented there. SDL_CreateGPUShader is not called in this case, it all happens inside the compute pipeline creation call.
Maybe a link / hint would help newbies like me understand that subtlety, as in vulkan you have to create your shaders separately from your pipelines, even for compute.