docs: disable systemd rate limits for CORS sync

docs/CHAT-RELAY.md

@@ -219,11 +219,9 @@ Create `/etc/systemd/system/simplex-cors-sync.service`:
 ```ini
 [Unit]
 Description=Sync SimpleX relay CORS config to Caddy
-StartLimitIntervalSec=30
-StartLimitBurst=10
+StartLimitIntervalSec=0
 [Service]
 Type=oneshot
-ExecStartPre=/bin/sleep 2
 ExecStart=/usr/local/bin/simplex-cors-sync.sh
 ```
 
@@ -236,6 +234,7 @@ After=caddy.service
 [Path]
 PathChanged=/var/www/relay-web-channels/cors.conf
 Unit=simplex-cors-sync.service
+TriggerLimitIntervalSec=0
 [Install]
 WantedBy=multi-user.target
 ```