docs: add changelog

Author: Ronald-TR

CHANGELOG.md

@@ -10,7 +10,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## Version 1.26.0/0.47b0 (2024-07-23)
 
 ### Added
-
+- `opentelemetry-instrumentation-aws-lambda` Avoid exception when a handler is not present.
+  ([#2750](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2750))
 - `opentelemetry-instrumentation-flask` Add `http.route` and `http.target` to metric attributes
   ([#2621](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2621))
 - `opentelemetry-instrumentation-aws-lambda` Enable global propagator for AWS instrumentation