clarify usability of stark2snark on various architectures

[pdg744]

In theory and according to our docs, one can use our tooling locally or remotely.
But in practice, the stark2snark prover only works on some hardware.
This is a frequent point of confusion for users -- would be good to clarify the current status and recommended workflow(s) in the docs.

[linear]

ZKVM-426 clarify usability of stark2snark on various architectures

[nuke-web3]

This was a major issue twice for users in the past two weeks

• https://discord.com/channels/953703904086994974/1243250690344751227/1244567425349849138
• https://discord.com/channels/953703904086994974/953703904086994977/1241971552312889396

I would propose to highlight this in the docs somewhat strongly ASAP if #1749 is not priority to resolve very soon.

[nuke-web3]

Idea: could we insert a compile time error to mention this issue until it's resolved for those using metal and other non-supported GPUs? Would help users a ton while this is not resolved

[austinabell]

Idea: could we insert a compile time error to mention this issue until it's resolved for those using metal and other non-supported GPUs? Would help users a ton while this is not resolved

Can't really do that given the prover is selected at runtime rather than compile time (through env variables).