add release notes

Author: jj22ee

.github/workflows/release-udp-exporter.yml

@@ -81,5 +81,6 @@ jobs:
         run: |
           gh release create --target "$GITHUB_REF_NAME" \
             --title "Release aws-distro-opentelemetry-exporter-xray-udp v${{ inputs.udp-exporter-version }}" \
+            --notes "Please refer to the [Changelog](https://github.com/aws-observability/aws-otel-ruby/blob/main/exporter/xray-udp/CHANGELOG.md) for more details" \
             --draft \
             "v${{ inputs.udp-exporter-version }}"