Validate and correct change log after 2.8 release (#4275)

Signed-off-by: Su <szhongna@amazon.com>

Author: zhongnansu

CHANGELOG.md

@@ -17,10 +17,10 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 ### 📈 Features/Enhancements
 
-- [Multiple DataSource] Add support for SigV4 authentication ([#3058](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3058)). Backwards-compatible feature included in v2.6.0 release.
 - Add plugin manifest config to define OpenSearch plugin dependency and verify if it is installed on the cluster ([#3116](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3116))
 - Replace re2 with RegExp in timeline and add unit tests ([#3908](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3908))
 - Add category option within groups for context menus ([#4144](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4144))
+- [Saved Object Service] Add Repository Factory Provider ([#4149](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4149))
 
 ### 🐛 Bug Fixes
 
@@ -56,7 +56,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 ### 🔩 Tests
 
-## [2.8.0 - TBD](https://github.com/opensearch-project/OpenSearch-Dashboards/releases/tag/2.8.0)
+## [2.8.0 - 2023-06-06](https://github.com/opensearch-project/OpenSearch-Dashboards/releases/tag/2.8.0)
 
 ### Deprecations
 
@@ -71,7 +71,6 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - [Multiple Datasource] Support Amazon OpenSearch Serverless ([#3957](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3957))
 - Add support for Node.js >=14.20.1 <19 ([#4071](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4071))
 - Bundle Node.js 14 as a fallback for operating systems that cannot run Node.js 18 ([#4151](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4151))
-- [Saved Object Service] Add Repository Factory Provider ([#4149](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4149))
 - Enhance grouping for context menus ([#3924](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3924))
 
 ### 🐛 Bug Fixes