Documentation for SDL3 environment variables

[p2ndemic]

Regarding the documentation for SDL3 environment variables.

With the migration from SDL2 to SDL3 https://github.com/libsdl-org/SDL/blob/main/docs/README-migration.md, some of the environment variable names have changed. [SDL_VIDEODRIVER → SDL_VIDEO_DRIVER | SDL_AUDIODRIVER → SDL_AUDIO_DRIVER, etc]
As a user, I would like to request creating a dedicated section on the libsdl.org website that documents the new SDL3 environment variables.

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The old environment variables SDL_VIDEODRIVER and SDL_AUDIODRIVER, even for me as a non-programmer and just a regular user, look ugly and annoying. That’s why I don’t mind if they are completely removed in SDL3. Sooner or later, users and developers will adopt the new variables - the key point is to create a dedicated section in the documentation for SDL3 environment variables, so that search engines and AI can properly index it.

At the moment, if you search in google for "sdl environment variables", the very first result still points to the SDL 1 documentation:
https://www.libsdl.org/release/SDL-1.2.15/docs/html/sdlenvvars.html

Thank you

[icculus]

We should probably automate this, so we generate some environment variable focused equivalent of the list here:

https://wiki.libsdl.org/SDL3/CategoryHints