Update CHANGELOG.md

Author: xrmx

CHANGELOG.md

@@ -15,7 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - `opentelemetry-instrumentation-fastapi`: fix wrapping of middlewares
   ([#3012](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3012))
-- `opentelemetry-instrumentation-urllib3` Proper bucket boundaries in stable semconv http duration metrics
+- `opentelemetry-instrumentation-urllib3`: proper bucket boundaries in stable semconv http duration metrics
   ([#3518](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3518))
 
 ### Breaking changes