Add Kubernetes deployment guide

[terrytangyuan]

This PR moves some content from the recent blog post to here as a more official guide for users who'd like to deploy Llama Stack on Kubernetes.

[ellistarn]

Hey I did something similar a few days ago: https://github.com/ellistarn/llama-operator/blob/main/manifest/deployment.yaml

[ellistarn]

There's an open question to me as to whether or not Kubernetes maps to the Llama Stack "distribution" concept. Many of these steps would not hold true for running w/ meta-reference or ollama. This feels like a sibling of https://github.com/meta-llama/llama-stack/blob/39c34dd25f9365b09000a07de5c46dbdba27e3cb/distributions/remote-vllm/compose.yaml.

However, there is substantial overlap between the compose files for each distribution, so I think we can do better. I think we probably need to figure out how to draw the right boundaries around distributions and deployment options. In the meantime, WDYT about moving this there?

[terrytangyuan]

We were discussing the same idea on Discord. My initial thought was to first provide a guide so that others can start following similar ways to deploy their selected providers to K8s (and make any necessary changes to meet their needs). Next step is to provide a packaged YAML file that's templated for K8s deployment for each provider (e.g. remote:vllm) and then we can simplify this guide. I believe we'll need a guide anyways to call out specific details.

[ellistarn]

I'll leave this call to the maintainers :)

[terrytangyuan]

@ellistarn Thanks for the review and suggestions! It's great to cross paths here again