Document the instance stats fix

CHANGELOG.md

@@ -39,6 +39,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Logger: default log level changed from `warn` to `info`.
 - Config mix task `migrate_to_db` truncates `config` table before migrating the config file.
 - Default to `prepare: :unnamed` in the database configuration.
+- Instance stats are now loaded on startup instead of being empty until next hourly job.
 <details>
   <summary>API Changes</summary>