Add release notes for 3.4.0 (#680)

Signed-off-by: opensearch-ci <opensearch-infra@amazon.com>

Author: opensearch-ci-bot

release-notes/opensearch-skills.release-notes-3.4.0.0.md

@@ -0,0 +1,9 @@
+## Version 3.4.0 Release Notes
+
+Compatible with OpenSearch and OpenSearch Dashboards version 3.4.0
+
+### Enhancements
+* Increase max_sample_count to 5 for log insight ([#678](https://github.com/opensearch-project/skills/pull/678))
+
+### Infrastructure
+* Gradle 9.2.0 and GitHub Actions JDK 25 Upgrade ([#675](https://github.com/opensearch-project/skills/pull/675))