docs: update kafka-logger plugin documentation

[Yilialinn]

Summary

• Add canonical link to API7 docs
• Update frontmatter description to better reflect plugin capabilities
• Fix Required column: optional → False for producer_batch_num, producer_batch_size, producer_max_buffering, producer_time_linger, and meta_refresh_interval; fix brokers.port type string → integer in ZH doc
• Replace minimal "Enable Plugin" and "Example usage" sections with three comprehensive examples:
  1. Log in Different Meta Log Formats — includes Docker Compose setup, full route configuration, and comparison of default vs origin log output
  2. Log Request and Response Headers With Plugin Metadata — demonstrates using plugin metadata with built-in variables to capture custom request/response headers
  3. Log Request Bodies Conditionally — shows include_req_body + include_req_body_expr for conditional body logging
• Remove "Delete Plugin" section
• Add admin_key note block before the first Admin API curl example

[Copilot]

Pull request overview

Updates the Kafka Logger plugin documentation (EN/ZH) to better describe batching + customizable log formats, align attribute tables, and provide richer end-to-end configuration examples for common logging scenarios.

Changes:

• Add canonical links and update frontmatter descriptions in both EN and ZH docs.
• Refresh attributes / plugin-metadata tables and add an admin_key note before Admin API examples.
• Replace the previous minimal usage sections with three expanded, scenario-based examples (meta formats, plugin metadata headers, conditional request body logging).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 6 comments.

File	Description
docs/zh/latest/plugins/kafka-logger.md	Updates Chinese kafka-logger docs: canonical link, revised attribute tables, and expanded examples.
docs/en/latest/plugins/kafka-logger.md	Updates English kafka-logger docs: canonical link, revised attribute tables, and expanded examples.

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[kayx23]

The new Kafka examples look like they may be broken as written: they configure the plugin to send logs to kafka:29092, but the docs only show Kafka/ZooKeeper being started in a separate kafka_net Docker Compose network and do not show APISIX joining that network. Unless APISIX is also attached to kafka_net, kafka:29092 will not resolve from APISIX. Could you either document that networking prerequisite explicitly or switch the examples to an address that matches the shown setup?