docs: clarify ProviderStrategy vs ToolStrategy in response_format note (#1524)

## Overview

This PR fixes a confusing note in the `create_agent.response_format`
documentation. The original text implied that `ToolStrategy` is used
when passing a schema directly, which is incorrect. The update clarifies
that `ProviderStrategy` is automatically used for models that support
native structured output, and wrapping the schema explicitly is
optional.

## Type of change

**Type:** Update existing documentation

## Related issues/PRs

- GitHub issue: -
- Feature PR: -

## Checklist

- [x] I have read the [contributing guidelines](README.md)
- [ ] I have tested my changes locally using `docs dev`
- [ ] All code examples have been tested and work correctly
- [ ] I have used **root relative** paths for internal links
- [ ] I have updated navigation in `src/docs.json` if needed

Co-authored-by: Lauren Hirata Singh <[email protected]>

Author: benjamin-frost

src/oss/langchain/structured-output.mdx

@@ -272,12 +272,12 @@ Provider-native structured output provides high reliability and strict validatio
 
 :::python
 <Note>
-    If the provider natively supports structured output for your model choice, it is functionally equivalent to write `response_format=ProductReview` instead of `response_format=ToolStrategy(ProductReview)`. In either case, if structured output is not supported, the agent will fall back to a tool calling strategy.
+    If the provider natively supports structured output for your model choice, it is functionally equivalent to write `response_format=ProductReview` instead of `response_format=ProviderStrategy(ProductReview)`. In either case, if structured output is not supported, the agent will fall back to a tool calling strategy.
 </Note>
 :::
 :::js
 <Note>
-    If the provider natively supports structured output for your model choice, it is functionally equivalent to write `responseFormat: contactInfoSchema` instead of `responseFormat: toolStrategy(contactInfoSchema)`. In either case, if structured output is not supported, the agent will fall back to a tool calling strategy.
+    If the provider natively supports structured output for your model choice, it is functionally equivalent to write `responseFormat: contactInfoSchema` instead of `responseFormat: providerStrategy(contactInfoSchema)`. In either case, if structured output is not supported, the agent will fall back to a tool calling strategy.
 </Note>
 :::