Adds release notes for v2.0.2. (#219)

Signed-off-by: David Venable <dlv@amazon.com>

Author: dlvenable

release-notes/logstash-output-opensearch-release-notes-2.0.2.md

@@ -0,0 +1,10 @@
+## Version 2.0.2 Release Notes
+
+Compatible with OpenSearch 1.3+, 2.0+
+
+### Bug Fixes
+* Encode body before signing to match manticore adapter encoding. ([#207](https://github.com/opensearch-project/logstash-output-opensearch/issues/207))
+
+### Documentation
+* Baselines the MAINTAINERS.md and CODEOWNERS files. ([#196](https://github.com/opensearch-project/logstash-output-opensearch/issues/196))
+