added changelog

Author: keith-decker

util/opentelemetry-util-genai/CHANGELOG.md

@@ -8,4 +8,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## Unreleased
 
 Repurpose the `OTEL_INSTRUMENTATION_GENAI_CAPTURE_MESSAGE_CONTENT` environment variable when GEN AI stability mode is set to `gen_ai_latest_experimental`,
-to take on an enum (`NO_CONTENT/SPAN_ONLY/EVENT_ONLY/SPAN_AND_EVENT`) instead of a boolean. Add a utility function to help parse this environment variable.
+to take on an enum (`NO_CONTENT/SPAN_ONLY/EVENT_ONLY/SPAN_AND_EVENT`) instead of a boolean. Add a utility function to help parse this environment variable.
+## [Unreleased]
+
+### Added
+
+- Generate Spans for LLM invocations
+- Generate Metrics for LLM invocations
+- Generate Logs for LLM invocations
+- Helper functions for starting and finishing LLM invocations