markdown lint

Author: ethandmd

CHANGELOG.md

@@ -14,14 +14,15 @@ Increment the:
 * PATCH version when you make backwards compatible bug fixes.
 
 ## [1.21 2025-04-04]
+
 * [SDK] Base2 exponential histogram aggregation
   [#3175](https://github.com/open-telemetry/opentelemetry-cpp/pull/3346)
 
   New Features:
 
   Add base2 exponential histogram aggregation. Includes a new aggregation type,
   ostream exporter, and otlp/grpc exporter. Updated histogram aggregation and
-  benchmark tests. 
+  benchmark tests.
 
 ## [Unreleased]