docs: update changelog for version 3.6.2

- Add Elasticsearch index_exists method documentation
- Document CI/CD pipeline enhancements
- Include Kafka test reliability improvements
- Add PostgreSQL DSN type safety fixes
- Document dependency updates and bug fixes
- Acknowledge community contributions

Author: HosseinNejatiJavaremi

docs/changelog.md

@@ -2,7 +2,7 @@
 
 All notable changes to ArchiPy are documented in this changelog, organized by version.
 
-## [3.6.2] - 2025-08-16
+## [3.7.0] - 2025-08-16
 
 ### New Features