add changelog

Author: lalitb

opentelemetry-sdk/CHANGELOG.md

@@ -8,6 +8,13 @@
   transparent change.
   [#2338](https://github.com/open-telemetry/opentelemetry-rust/pull/2338)
 
+- *Breaking* LogExporter::export() method doesn't take mutable reference to self:
+  Before:
+     async fn export(&mut self, _batch: LogBatch<'_>) -> LogResult<()>
+  After:
+     async fn export(&self, _batch: LogBatch<'_>) -> LogResult<()>
+  The custom exporters would need to internally synchronize their mutable states (if any)
+
 ## 0.27.1
 
 Released 2024-Nov-27