Update OpenAPI generator to add param and field documentation (#896)

We desperately need to document our APIs. This is the basic requirement
of having a Spec :)

This PR updates the OpenAPI generator so documentation for request
parameters and object fields can be properly added to the OpenAPI specs.
From there, this should get picked by Stainless, etc.

## Test Plan:

Updated client-sdk (See
https://github.com/meta-llama/llama-stack-client-python/pull/104) and
then ran:

```bash
cd tests/client-sdk
LLAMA_STACK_CONFIG=../../llama_stack/templates/fireworks/run.yaml pytest -s -v inference/test_inference.py agents/test_agents.py
```

docs/openapi_generator/generate.py

@@ -36,6 +36,16 @@ from .pyopenapi.specification import Info, Server  # noqa: E402
 from .pyopenapi.utility import Specification  # noqa: E402
 
 
+def str_presenter(dumper, data):
+    if data.startswith(f"/{LLAMA_STACK_API_VERSION}") or data.startswith(
+        "#/components/schemas/"
+    ):
+        style = None
+    else:
+        style = ">" if "\n" in data or len(data) > 40 else None
+    return dumper.represent_scalar("tag:yaml.org,2002:str", data, style=style)
+
+
 def main(output_dir: str):
     output_dir = Path(output_dir)
     if not output_dir.exists():
@@ -69,7 +79,8 @@ def main(output_dir: str):
         y.sequence_dash_offset = 2
         y.width = 80
         y.allow_unicode = True
-        y.explicit_start = True
+        y.representer.add_representer(str, str_presenter)
+
         y.dump(
             spec.get_json(),
             fp,