Add release notes for 2.8 (#705)

Signed-off-by: Joshua Li <[email protected]>
(cherry picked from commit f27cdd4)

Author: joshuali925

release-notes/opensearch-reporting.release-notes-2.8.0.0.md

@@ -0,0 +1,10 @@
+## Version 2.8.0.0 Release Notes
+
+Compatible with OpenSearch 2.8.0
+
+### Bug Fixes
+* Update json version to 20230227 ([#692](https://github.com/opensearch-project/reporting/pull/692))
+* Update Gradle Wrapper to 7.6.1 ([#695](https://github.com/opensearch-project/reporting/pull/695))
+
+### Maintenance
+* Increment version to 2.8.0-SNAPSHOT ([#688](https://github.com/opensearch-project/reporting/pull/688))