Clarify usage of response_format with Anthropic models

[kathayl]

Added caution note regarding Anthropic models and response_format.

Summary

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[github-actions]

This pull request requires reviews from CODEOWNERS as it changes files that match the following patterns:

Pattern	Owners
/src/content/docs/browser-rendering/	@mchenco, @cloudflare/pcx-technical-writing, @celso, @kathayl, @ToriLindsay

[github-actions]

Preview URL: https://1fa3893e.preview.developers.cloudflare.com
Preview Branch URL: https://kathayl-patch-15.preview.developers.cloudflare.com

Files with changes (up to 15)

Original Link	Updated Link
https://developers.cloudflare.com/browser-rendering/rest-api/json-endpoint/	https://kathayl-patch-15.preview.developers.cloudflare.com/browser-rendering/rest-api/json-endpoint/