Document capabilities in `docs` directory

[nathan-weinberg]

It would be cool to detail all of the different things we have enabled in https://github.com/containers/ramalama-stack/blob/main/src/ramalama_stack/ramalama-run.yaml in terms of Llama Stack providers and gave some context and examples around these to show what you can do with ramalama-stack beyond the basic inference test details in the README