Add Fleet and Elastic Agent 9.0.2 Release Notes (#1483)

Part of elastic/observability-docs#4902

Adds the Fleet and Elastic Agent 9.0.2 Release Notes:

- [x] Fleet contents from:
elastic/fleet-server#4960
- [x] Elastic Agent contents from:
elastic/elastic-agent#8231
- [x] ~~Any related content from
elastic/kibana#221237

---------

Co-authored-by: Aleksandra Spilkowska <96738481+alexandra5000@users.noreply.github.com>

Author: colleenmcginnis

release-notes/fleet-elastic-agent/index.md

@@ -26,6 +26,20 @@ To check for security updates, go to [Security announcements for the Elastic sta
 % ### Fixes [fleet-elastic-agent-next-fixes]
 % *
 
+## 9.0.2 [fleet-elastic-agent-9.0.2-release-notes]
+
+### Features and enhancements [fleet-elastic-agent-9.0.2-features-enhancements]
+
+fleet-server::
+
+* Updates Go version to v1.24.3 in {{fleet}} [#4891]({{fleet-server-pull}}4891)
+	
+* Updates Go version to v1.24.3 in {{agent}} [#8109]({{agent-pull}}8109)
+
+### Fixes [fleet-elastic-agent-9.0.2-fixes]
+
+* Improves the upgrade process for {{agent}} installed using DEB or RPM packages by copying the run directory from the previous installation into the new version's folder [#7999]({{agent-pull}}7999) [#3832]({{agent-issue}}3832)
+
 ## 9.0.1 [fleet-elastic-agent-9.0.1-release-notes]
 
 ### Features and enhancements [fleet-elastic-agent-9.0.1-features-enhancements]