[documentation] missing README for request-metadata-extractor plugin #194

What happened:

The request-metadata-extractor datalayer plugin (pkg/framework/plugins/datalayer/requestmetadata/) has no README.md. There is no documentation describing what the plugin does, how it tracks in-flight requests and token counts, the attribute it writes to the datastore, or its known limitations around counter drift.

What you expected to happen:

A README.md exists in the plugin directory that documents:

• Purpose and behavioral intent of the plugin
• How RequestEventType and ResponseEventType events are processed
• The request-metadata attribute written to the datastore and its fields
• Known limitations (counter drift on connection drops / missing ResponseEventType)
• Concurrency assumptions

How to reproduce it (as minimally and precisely as possible):

1. Navigate to pkg/framework/plugins/datalayer/requestmetadata/.
2. Observe that only plugin.go and plugin_test.go are present — no README.md.

Anything else we need to know?:

Other plugins in the repository include a README.md following a consistent format. The request-metadata-extractor plugin should follow the same convention.

Environment:

• Kubernetes version (use kubectl version): N/A
• llm-d-scheduler version (use git describe --tags --dirty --always if you built from source, or specify the tag if you used a tagged version or image): N/A
• Cloud provider or hardware configuration: N/A
• Install tools: N/A
• Others: N/A