Add changelog

Author: xrmx

CHANGELOG.md

@@ -11,6 +11,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Added
+
+- `opentelemetry-instrumentation-httpx`: add support for url exclusions via `OTEL_PYTHON_EXCLUDED_URLS` / `OTEL_PYTHON_HTTPX_EXCLUDED_URLS`
+  ([#3837](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3837))
+
 ## Version 1.38.0/0.59b0 (2025-10-16)
 
 ### Fixed