Add R9700 AI Pro to the list of supported gfx120X cards in the README

[boecks]

Describe the feature you'd like
Add AMD R9700 AI Pro as supported card in the README for the list of known supported gfx120X RDNA4 GPUs

Why would this be useful?
This GPU is specifically targeted and marketed for local AI Inference and honestly, it works excellent with llamacpp-rocm (an Lemonade Server). It should be unambiguous that this card works with this software to inform (potential) users of this card sufficiently.

Any additional context?

[danielholanda]

@slojosic-amd Consulting you here. Any objections to adding this? Looks like it is already supported by our build. I can add the documentation if that is indeed the case.