Show request body examples in docs

[kafkasl]

An OpenAPI request body can carry examples in two places:

1. Whole-payload examples, sitting next to the schema: named sample request bodies under examples (or the OpenAPI 3.0 singular example).
2. Per-parameter examples, sitting inside the schema: sample values attached to individual properties.

Runpod's POST /v2/pods, the case that prompted this PR, has both. Next to the schema:

content:
  application/json:
    schema:
      $ref: "#/components/schemas/CreatePodRequest"
    examples:
      gpuPod:
        summary: GPU pod
        value:
          name: pytorch-training
          image: runpod/pytorch:1.0.2-cu1281-torch280-ubuntu2404
          gpu:
            id: NVIDIA GeForce RTX 4090
            count: 1
          disk: 50

And inside CreatePodRequest:

name:
  type: string
  minLength: 1
  examples:
  - my-training-pod

We drop both kinds. This is made worse by the fact we only parse the top level of the schema. A nested object param comes out typed as bare dict, and everything beneath it is discarded. For example the doc() on this op shows:

- gpu (dict, optional): GPU request for a pod create. Carries the CUDA host constraints, which live here rather than at the body's top level so they are unrepresentable on a CPU pod.

The caller can't construct a valid body without going back to the raw spec.

I decided to improve this by adding the 1. Whole-payload examples into the docs. It is a concise fix and displaying the main payload examples should mitigate the issue in most happy-paths.

Nothing changes when a spec has no examples.