[InferenceModel update] Document all new changes

[kfswain]

This is related to: https://github.com/kubernetes-sigs/gateway-api-inference-extension/tree/main/docs/proposals/1199-inferencemodel-api-evolution#structure-change

We need to document all the API changes in our site & give examples consuming these new configuration levels.

[ahg-g]

As part of this, we also need to update Criticality to Priority

[danehans]

FYI- the API docs generator is broken: #1421

[nirrozenbaum]

@kfswain can we close this issue as completed?