Adding Changelog

Signed-off-by: Shourya Dutta Biswas <114977491+shourya035@users.noreply.github.com>

CHANGELOG-3.0.md

@@ -13,6 +13,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - GHA to verify checklist items completion in PR descriptions ([#10800](https://github.com/opensearch-project/OpenSearch/pull/10800))
 - Allow to pass the list settings through environment variables (like [], ["a", "b", "c"], ...) ([#10625](https://github.com/opensearch-project/OpenSearch/pull/10625))
 - Views, simplify data access and manipulation by providing a virtual layer over one or more indices ([#11957](https://github.com/opensearch-project/OpenSearch/pull/11957))
+- Adding translog durability validation in index templates ([#15494](https://github.com/opensearch-project/OpenSearch/pull/15494))
 
 ### Dependencies