Adding IPv6 gateway setting + dhcpd.service fix

miscellaneous/dhcpd.service

+[Unit]
+Description=DHCPv4 Server Daemon
+Documentation=man:dhcpd(8) man:dhcpd.conf(5)
+Wants=network-online.target
+After=network-online.target
+After=time-sync.target
+Requires=firewall.service
+After=firewall.service
+
+[Service]
+Restart=always  
+StartLimitBurst=5
+RestartSec=60
+Type=notify
+ExecStart=/sbin/ip netns exec fw /usr/sbin/dhcpd -f -cf /etc/dhcp/dhcpd.conf -user dhcpd -group dhcpd --no-pid
+
+[Install]
+WantedBy=multi-user.target