[imitater-dou]

Summary

sink/README.md was carried over from the standalone substreams-sink repository when the sink library moved into this repo (#658). Two parts of it no longer match the code in sink/:

1. Missing example links: the README links to ./examples/basic/ and ./examples/advanced/ (main.go + README.md), but sink/examples/ only contains simple-sink/. All 5 links 404 on GitHub.
2. Metrics snippet doesn't compile: the "Monitoring and Statistics" snippet uses sink.ProgressMessageProcessedBytes, sink.ProgressMessageTotalProcessedBlocks and sink.DataMessageSizeBytes, none of which exist in the package. The current metrics in sink/metrics.go are ProcessedBytes, ProcessedBlocks (gauges) and MessageSizeBytes (counter). Also, dmetrics Gauge.Get()/Counter.Get() return float64, so %d prints %!d(float64=...).

Changes

• Point the examples section at ./examples/simple-sink/main.go, and replace the "use the Advanced Example" note with a pointer to the existing Example Implementations section (the production sinks for MongoDB/PostgreSQL, etc.).
• Use the existing metric variables in the snippet and format them with %.0f.

Docs only. No code changes.

How to verify

ls sink/examples/                      # only simple-sink/
grep -rn "ProgressMessageProcessedBytes\|ProgressMessageTotalProcessedBlocks\|DataMessageSizeBytes" --include=*.go .   # no matches
grep -n "ProcessedBytes\|ProcessedBlocks\|MessageSizeBytes" sink/metrics.go

[sduchesneau]

LGTM