Update kvm.rst - iptables before rule

On Ubuntu 24.04 LTS I found the described issue with the forwarding traffic back and fourth from guests system VMs and the physical interfaces attached to the bridges. This solved my problems.

Author: daviftorres

source/installguide/hypervisor/kvm.rst

@@ -1551,8 +1551,8 @@ To open the required ports, execute the following commands:
    sudo vi /etc/ufw/before.rules
 
 .. parsed-literal::
-   -A FORWARD -d 192.168.42.11 -j ACCEPT
-   -A FORWARD -s 192.168.42.11 -j ACCEPT
+   -A FORWARD -d 192.168.42.0/24 -j ACCEPT
+   -A FORWARD -s 192.168.42.0/24 -j ACCEPT
 
 
 Additional Packages Required for Features