Add a changelog entry

CHANGELOG.md

@@ -22,6 +22,7 @@ System:
 * On low-usage systems, don't hold backups for quite so long by taking a full backup more often.
 * Nightly status checks might fail if any domains had non-ASCII characters.
 * If domains need a TLS certificate and the user hasn't installed one yet using Let's Encrypt, the administrator would get a nightly email with weird interactive text asking them to agree to Let's Encrypt's ToS. Now just say that the provisioning can't be done automatically.
+* Reduce the number of background processes used by the management daemon to lower memory consumption
 
 Setup: