Fix CHANGELOG sections

Author: 2opremio

services/horizon/CHANGELOG.md

@@ -7,10 +7,13 @@ file. This project adheres to [Semantic Versioning](http://semver.org/).
 
 **Upgrading to this version from <= v2.8.3 will trigger a state rebuild. During this process (which will take at least 10 minutes), Horizon will not ingest new ledgers.**
 
+### Changes
+
+- Bump Go to the latest version, including net/http and net/url security fixes ([4577](https://github.com/stellar/go/pull/4577))
+
 ### DB Schema Migration
 
 - Added indexes by id for assets in the respective `history_trades` tables. Ingestion will stop while the migration is being applied. ([4565](https://github.com/stellar/go/pull/4565))
-- Bump Go to the latest version, including net/http and net/url security fixes ([4577](https://github.com/stellar/go/pull/4577))
 
 ## 2.20.0