libvirtd.conf: Fix invalid default of max_anonymous_clients

https://bugzilla.redhat.com/show_bug.cgi?id=1343442

When a client connects, it is placed into a queue. As soon as it
authenticate, it is taken out of that queue and placed into a
different one. Now, we have a setting in the daemon config file
that allows users to control the length of the queue of yet not
authenticated clients. By default, it has a value 20 but in the
description to the config knob we clam it's zero.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

daemon/libvirtd.conf

@@ -283,8 +283,8 @@
 #max_queued_clients = 1000
 
 # The maximum length of queue of accepted but not yet
-# authenticated clients. The default value is zero, meaning
-# the feature is disabled.
+# authenticated clients. The default value is 20. Set this to
+# zero to turn this feature off.
 #max_anonymous_clients = 20
 
 # The minimum limit sets the number of workers to start up