docs: add notes for #6065 #7232 and #5216

CHANGELOG.md

 # 4.3.0 (unreleased)
 
+## Enhancements
+
+* **InfluxDB**: influxdb query builder support for ORDER BY and LIMIT (allows TOPN queries) [#6065](https://github.com/grafana/grafana/issues/6065) Support influxdb's SLIMIT Feature [#7232](https://github.com/grafana/grafana/issues/7232) thx [@thuck](https://github.com/thuck)
+* **Panels**: Delay loading & Lazy load panels as they become visible (scrolled into view) [#5216](https://github.com/grafana/grafana/issues/5216) thx [@jifwin](https://github.com/jifwin)
+
 ## Minor Enchancements
 
+
 # 4.2.0-beta2 (unreleased)
 ## Minor Enhancements
 * **Templates**: Prevent use of the prefix `__` for templates in web UI [#7678](https://github.com/grafana/grafana/issues/7678)