slapos.cfg.example: Reload firewalld with a firewall-cmd

Thanks to this it's possible to catch issues with firewalld

slapos.cfg.example

@@ -40,7 +40,7 @@ use_unique_local_address = False
 dbus_executable = /opt/slapos/parts/dbus/bin/dbus-daemon --nofork --nopidfile --system
 firewall_executable = /opt/slapos/parts/firewalld/sbin/firewalld --nofork --nopid --log-file /opt/slapos/log/firewalld-process.log
 firewall_cmd = /opt/slapos/parts/firewalld/bin/firewall-cmd
-reload_config_cmd = slapos node restart firewall
+reload_config_cmd = /opt/slapos/parts/firewalld/bin/firewall-cmd --reload
 log_file = /opt/slapos/log/firewalld.log
 dbus_log_file = /opt/slapos/log/dbus.log
 # Authorized IP address sources