Added command to set libvirtd to traditional mode

Author: Dav-11

source/installguide/hypervisor/kvm.rst

@@ -478,6 +478,12 @@ cloudstack-agent and should already be installed.
    .. parsed-literal::
       remote_mode="legacy"
 
+   Set libvirtd mode to traditional mode (see https://libvirt.org/manpages/libvirtd.html#system-socket-activation):
+   
+   .. parsed-literal::
+      systemctl mask libvirtd.socket libvirtd-ro.socket \
+         libvirtd-admin.socket libvirtd-tls.socket libvirtd-tcp.socket
+
 
 #. Restart libvirt