fix dns64 figure as good as it gets

Signed-off-by: Nico Schottelius <nico@nico-notebook.schottelius.org>

doc/graphviz/dns64.dot

@@ -13,14 +13,14 @@ digraph G {
     v4host1 [ label="IPv4 host: 192.0.2.0" ];
 
 
-    subgraph sdns64 {
+    subgraph cluster_dns64 {
         label="DNS request";
 
         dnsserver;
         authdns;
     }
 
-    subgraph snat64 {
+    subgraph cluster_nat64 {
         label="NAT64 translation";
         nat64;
         v4host1;
@@ -34,8 +34,8 @@ digraph G {
     authdns->dnsserver [ label="NO AAAA record"];
     authdns->dnsserver [ label="A: 192.0.2.0"];
 
-    v6host1->nat64 [ label="Packet for\n64:ff9b::c000:200 tcp port 80" ];
-    nat64->v4host1 [ label="Packet for\n192.0.2.0 tcp port 80" ];
+    v6host1->nat64 [ label="Packet for\n64:ff9b::c000:200\ntcp port 80" ];
+    nat64->v4host1 [ label="Packet\n for 192.0.2.0\ntcp port 80" ];
 
 
 }