Adding release notes for 2.7.0 (#428)

Signed-off-by: Khushboo Rajput <khushbr@amazon.com>
(cherry picked from commit b8450d2)

release-notes/opensearch-performance-analyzer.release-notes-2.7.0.0.md

@@ -0,0 +1,20 @@
+## Version 2.7.0 Release Notes
+
+Compatible with OpenSearch 2.7.0
+
+## Enhancements
+* Adding CIRCUIT_BREAKER_COLLECTOR_EXECUTION_TIME, CIRCUIT_BREAKER_COLLECTOR_ERROR, CLUSTER_MANAGER_METRICS_ERROR in StatExceptionCode ([420](https://github.com/opensearch-project/performance-analyzer/pull/420/))
+* Adding Shard HotSpot feature in RCA ([295](https://github.com/opensearch-project/performance-analyzer-rca/pull/295))
+
+### Bug fixes
+* Fix AdmissionControl class loading issue in Netty/PA communication ([#414](https://github.com/opensearch-project/performance-analyzer/pull/414))
+* Fix GC metric not collected in RCA ([287](https://github.com/opensearch-project/performance-analyzer-rca/pull/287))
+* Fix ShardEvents and ShardBulkDocs null metrics in RCA ([283](https://github.com/opensearch-project/performance-analyzer-rca/pull/283))
+
+### Infrastructure
+* Getting Jackson,JUnit, Log4j dependency version from core ([#417](https://github.com/opensearch-project/performance-analyzer/pull/417))
+* Upgrade checkstyle to 9.3 ([#395](https://github.com/opensearch-project/performance-analyzer/pull/395))
+* Publish snapshots to maven via GHA ([#385](https://github.com/opensearch-project/performance-analyzer/issues/385))
+
+### Maintenance
+* Modify namespace from xcontent common to core ([#410](https://github.com/opensearch-project/performance-analyzer/pull/410))