docs(readme): reference pydantic helpers (#138)

README.md

@@ -166,9 +166,9 @@ async for completion in stream:
 
 ## Using Types
 
-Nested request parameters are [TypedDicts](https://docs.python.org/3/library/typing.html#typing.TypedDict), while responses are [Pydantic](https://pydantic-docs.helpmanual.io/) models. This helps provide autocomplete and documentation within your editor.
+Nested request parameters are [TypedDicts](https://docs.python.org/3/library/typing.html#typing.TypedDict). Responses are [Pydantic models](https://docs.pydantic.dev), which provide helper methods for things like serializing back into json ([v1](https://docs.pydantic.dev/1.10/usage/models/), [v2](https://docs.pydantic.dev/latest/usage/serialization/)). To get a dictionary, you can call `dict(model)`.
 
-If you would like to see type errors in VS Code to help catch bugs earlier, set `python.analysis.typeCheckingMode` to `"basic"`.
+This helps provide autocomplete and documentation within your editor. If you would like to see type errors in VS Code to help catch bugs earlier, set `python.analysis.typeCheckingMode` to `"basic"`.
 
 ## Token counting