Docs: update match.md

[filiperochalopes]

🔧 Summary of Changes – $match Endpoint Documentation

🎯 Purpose

Update the documentation for the $match endpoint to clarify usage and reflect recent improvements.

➕ Additions

• Added a note indicating that the __index field (zero-based) is mandatory for each row in the response.
• Introduced a new section titled “Batching & Concurrency” to explain how batch processing works and how two concurrent requests are handled by default.
• Documented the optional search_normalized_score field (range 0–1) in the search_meta response object.

🔧 Adjustments

• Reorganized the Request section to include a “Request URL parameters” subtitle.
• Normalized the parameters table for clarity and consistency.
• Unified and renamed the examples section to “Examples”, now labeled Example 1 and Example 2.

💡 Examples

• Simplified Example 1 by removing local_id from the payload, adding the __index field in the response, and formatting the JSON for readability.
• Updated indentation and clarity in Example 2 for better understanding.

✅ Impact

• Documentation-only changes — no breaking changes or modifications to the API contract.
• Clarifies that __index is always returned and that search_normalized_score is optional.

📝 Modified File

• docs/source/oclapi/apireference/match.md