add changelog entry

Signed-off-by: Ted Kern <[email protected]>

Author: Arnatious

CHANGELOG.md

@@ -6,6 +6,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased](https://github.com/open-telemetry/opentelemetry-python/compare/v1.6.0-0.25b0...HEAD)
 
+- Fixed ReadableSpan property types attempting to create a mapping from a list
+  ([#2215](https://github.com/open-telemetry/opentelemetry-python/pull/2215))
 - Upgrade GRPC/protobuf related dependency and regenerate otlp protobufs
   ([#2201](https://github.com/open-telemetry/opentelemetry-python/pull/2201))
 - Propagation: only warn about oversized baggage headers when headers exist