Add 2.7 release note (#1504)

Author: dai-chen

release-notes/opensearch-observability.release-notes-2.7.0.0.md

@@ -0,0 +1,20 @@
+## Version 2.7.0.0 Release Notes
+
+Compatible with OpenSearch and OpenSearch Dashboards Version 2.7.0
+
+### Features
+
+- Create first Nginx Integration bundle ([#1442](https://github.com/opensearch-project/observability/pull/1442))
+- Add catalog meta info in the index template ([#1446](https://github.com/opensearch-project/observability/pull/1446))
+
+### Infrastructure
+
+- Automate releases based on tagging ([#1436](https://github.com/opensearch-project/observability/pull/1436))
+- Fix maven branch ([#1449](https://github.com/opensearch-project/observability/pull/1449))
+- Rename all SSO references to SS4O ([#1470](https://github.com/opensearch-project/observability/pull/1470))
+- [BACKPORT 2.x] Fix 2.x imports ([#1483](https://github.com/opensearch-project/observability/pull/1483))
+
+### Maintenance
+
+- Bump snakeyaml version ([#1465](https://github.com/opensearch-project/observability/pull/1465))
+