[CHORE] Add changelog entry for otelecho semconv migration

Author: Oloruntobi1

CHANGELOG.md

@@ -21,6 +21,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 ### Changed
 
 - Jaeger remote sampler's probabilistic strategy now uses the same sampling algorithm as `trace.TraceIDRatioBased` in `go.opentelemetry.io/contrib/samplers/jaegerremote`. (#6892)
+- - Migrated `otelecho` instrumentation to use OpenTelemetry semantic conventions (`semconv`) for HTTP attributes. (#6980)
 
 ### Fixed