add changelog entry for PR #738

Author: liustve

CHANGELOG.md

@@ -12,6 +12,8 @@ If your change does not need a CHANGELOG entry, add the "skip changelog" label t
 
 ## Unreleased
 
+- fix(agent-observability): fall back to OTEL_EXPORTER_OTLP_ENDPOINT for unsampled spans
+  ([#738](https://github.com/aws-observability/aws-otel-python-instrumentation/pull/738))
 - feat: auto-detect and mutually exclude AWS native vs third-party agentic instrumentors; add `AWS_AGENTIC_INSTRUMENTATION_OPT_IN` env var to override auto-detection
   ([#729](https://github.com/aws-observability/aws-otel-python-instrumentation/pull/729))
 - fix(lambda-layer): align context propagation with JS — delegate to global propagator so W3C traceparent is no longer ignored when X-Ray active tracing is enabled