[CHORE] Note the destroyed-session diagnostic in the changelog

Signed-off-by: thc1006 <84045975+thc1006@users.noreply.github.com>

Author: thc1006

CHANGELOG.md

@@ -83,6 +83,9 @@ Increment the:
   ([#4349](https://github.com/open-telemetry/opentelemetry-cpp/pull/4349))
 * [BUG] End the Elasticsearch exporter's wait on a read or write error
   [#4331](https://github.com/open-telemetry/opentelemetry-cpp/pull/4331)
+* [BUG] Say why an Elasticsearch export failed when the session was destroyed
+  before a response arrived
+  [#4331](https://github.com/open-telemetry/opentelemetry-cpp/pull/4331)
 
 * [CONFIGURATION] Add SDK component builder interfaces to the registry
   [#4358](https://github.com/open-telemetry/opentelemetry-cpp/issues/4358)