Update CHANGELOG

Author: drewby

instrumentation-genai/opentelemetry-instrumentation-openai-v2/CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add example to `opentelemetry-instrumentation-openai-v2`
   ([#3006](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3006))
 - Support for `AsyncOpenAI/AsyncCompletions` ([#2984](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2984))
+- Add metrics to the Python OpenAI instrumentation ([#3180](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3180))
 
 ## Version 2.0b0 (2024-11-08)