Add 2.8.0 release notes (#4204)

* Add 2.8.0 release notes

Co-authored-by: Josh Romero <rmerqg@amazon.com>
Signed-off-by: Kawika Avilla <kavilla414@gmail.com>
(cherry picked from commit 5ffb3d8)
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

release-notes/opensearch-dashboards.release-notes-2.8.0.md

@@ -0,0 +1,30 @@
+## Version 2.8.0 Release Notes
+
+### 🛡 Security
+
+- [CVE-2023-2251] Bump yaml to `2.2.2` ([#3947](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3947))
+
+### 📈 Features/Enhancements
+
+- [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))
+- Enhance grouping for context menus ([#3924](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3924))
+
+### 🐛 Bug Fixes
+
+- [BUG] Fix bottom bar visibility using createPortal ([#3978](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3978))
+
+### 🚞 Infrastructure
+
+- Add threshold to code coverage config to prevent workflow failures ([#4040](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4040))
+- [CI] Skip checksum verification on OpenSearch snapshot for cypress tests ([#4188](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4188))
+
+### 🛠 Maintenance
+
+- Use `exec` in the CLI shell scripts to prevent new process creation ([#3955](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3955))
+- Remove timeline application ([#3971](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3971))
+
+## 🎉 Welcome
+
+Thank you to all the first-time contributors who made this release possible: @sikhote, @SergeyMyssak!