changelog: adds note about closing #7107

CHANGELOG.md

 # 5.1.0 (unreleased)
 
 * **Postgres/MySQL**: Ability to insert 0s or nulls for missing intervals [#9487](https://github.com/grafana/grafana/issues/9487), thanks [@svenklemm](https://github.com/svenklemm)
-
+* **Graph**: Thresholds for Right Y axis [#7107](https://github.com/grafana/grafana/issues/7107), thx [@ilgizar](https://github.com/ilgizar)
 
 # 5.0.1 (unreleased)