Update CHANGELOG.md

Co-authored-by: Damien Mathieu <42@dmathieu.com>

Author: ash2k

CHANGELOG.md

@@ -50,7 +50,8 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ### Changed
 
-- Use more efficient `WithAttributeSet()` in `otelhttp` and `otelgrpc`. (#5664) 
+- Improve performance of `go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc` with the usage of `WithAttributeSet()` instead of `WithAttribute()`. (#5664) 
+- Improve performance of `go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp` with the usage of `WithAttributeSet()` instead of `WithAttribute()`. (#5664) 
 
 ## [1.27.0/0.52.0/0.21.0/0.7.0/0.2.0] - 2024-05-21