[docs] add configuration doc to deployment guide

[siddvenk]

This PR adds an updated configuration doc to the deployment guide. It is intended to be a comprehensive configuration guide in the context of LMI.

It walks through the important configurations, what they mean, and how to set them.

It also covers the same configurations we had in our previous doc, but in a list form rather than table form. The table form is harder to parse compared to the list form in my opinion, but let me know if you disagree.

It also covers the environment variable translation at the end. Most of the focus is on the serving.properties format.

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This is intended to reflect the state of V8. I know we are working on many improvements to minimized the required set of configs, but I am not confident in recommending auto currently because it can easily fall back to the slow huggingface accelerate backend, and it cannot be used to select vllm.

For the HF_MODEL_ID experience, I think that is better served in a separate doc. This doc is intended for advanced users that want a comprehensive overview.