add a changelog entry

Author: juliuskoval

src/OpenTelemetry.Api/CHANGELOG.md

@@ -6,6 +6,9 @@ Notes](../../RELEASENOTES.md).
 
 ## Unreleased
 
+* Added `Exception` property to `LogRecordData`.
+  ([#6980](https://github.com/open-telemetry/opentelemetry-dotnet/pull/6980))
+
 * **Breaking change:** The Baggage API implements the latest [Baggage API
   specification](https://github.com/open-telemetry/opentelemetry-specification/blob/v1.36.0/specification/baggage/api.md),
   which disallows empty baggage names and treats baggage names and values as case