Update documentation

[crimist]

• Add ampere verification for direct backend to docs
• Minor restructuring to improve clarity
• Add links to improve clarity

[crimist]

Does the direct backend still need the experimental warning etc? It does seem like very few people are having issues with it so I could clean it up and just add an line that says "here's an issue template if you have a problem". You're more familiar with the issue tracker though so lmk.

[elFarto]

Does the direct backend still need the experimental warning etc?

I think so. While it does appear to be working for everyone, it could easily break on the next driver upgrade. It's also not the NVIDIA supported way to do this, and relies on me guessing how the NVIDIA driver API works.

[crimist]

Ah I see, so it uses undocumented functions?

[elFarto]

Ah I see, so it uses undocumented functions?

That's correct.

[elFarto]

Thanks for the changes!