Prepare KarlDNS production deployment

.env.example

@@ -25,6 +25,7 @@ DDNS_TTL=60
 # DDNS_ADMIN_RATE_LIMIT_PER_MINUTE=20
 # DDNS_MAX_REQUEST_BODY_BYTES=16384
 # DDNS_REDACTED_ACCESS_LOG=0
+# DDNS_CLEANUP_PENDING_ACCOUNT_HOURS=24
 # DDNS_CLEANUP_UNUSED_ACCOUNT_HOURS=1080
 # DDNS_CLEANUP_EVENT_HISTORY_HOURS=4320
 # DDNS_CLEANUP_INTERVAL_SECONDS=3600