docs(core): improve style for refs

[mdrxy]

No description provided.

[Copilot]

Pull request overview

This PR modernizes documentation formatting in the with_structured_output method by converting plain text example headers to MkDocs Material collapsible admonition blocks. The changes follow the established documentation pattern in the LangChain Core codebase where the primary example is expanded by default (???+) and subsequent examples are collapsed (???), improving documentation readability and user experience.

Key Changes:

• Converted three example sections to use MkDocs Material admonition syntax
• Applied consistent 4-space indentation for all example content
• Preserved all original code examples and documentation content without modification

[codspeed-hq]

CodSpeed Performance Report

Merging #34227 will not alter performance

_{Comparing mdrxy/core-refs (ee824d5) with master (4a42158)}

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

Summary

✅ 13 untouched
⏩ 21 skipped¹

Footnotes

1. 21 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩