Fix tun documentation

docs/configuration/inbound/tun.md

@@ -11,7 +11,7 @@
   
   "interface_name": "tun0",
   "inet4_address": "172.19.0.1/30",
-  "inet6_address": "fdfe:dcba:9876::1/128",
+  "inet6_address": "fdfe:dcba:9876::1/126",
   "mtu": 9000,
   "auto_route": true,
   "strict_route": true,

docs/configuration/inbound/tun.zh.md

@@ -11,7 +11,7 @@
 
   "interface_name": "tun0",
   "inet4_address": "172.19.0.1/30",
-  "inet6_address": "fdfe:dcba:9876::1/128",
+  "inet6_address": "fdfe:dcba:9876::1/126",
   "mtu": 9000,
   "auto_route": true,
   "strict_route": true,