Add changelog

Author: xrmx

CHANGELOG.md

@@ -15,6 +15,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#4353](https://github.com/open-telemetry/opentelemetry-python/pull/4353))
 - sdk: don't log or print warnings when the SDK has been disabled
   ([#4371](https://github.com/open-telemetry/opentelemetry-python/pull/4371))
+- Add support for `explicit_bucket_boundaries` advisory for Histograms
+  ([#4361](https://github.com/open-telemetry/opentelemetry-python/pull/4361))
 
 ## Version 1.29.0/0.50b0 (2024-12-11)