add CHANGELOG entry

Author: dimastbk

CHANGELOG.md

@@ -11,6 +11,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Added
+- `opentelemetry-instrumentation-aiokafka` Add instrumentation of `consumer.getmany` (batch)
+  ([#3257](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3257))
+
 ### Fixed
 - `opentelemetry-instrumentation-redis` Add missing entry in doc string for `def _instrument`
   ([#3247](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3247))