fix: README missing comma

Author: zonyitoo

README.md

@@ -818,7 +818,7 @@ Example configuration:
     // Outbound socket bind() to this IP (choose a specific interface)
     "outbound_bind_addr": "11.22.33.44",
     // Outbound UDP socket allows IP fragmentation (default false)
-    "outbound_udp_allow_fragmentation": false
+    "outbound_udp_allow_fragmentation": false,
 
     // Balancer customization
     "balancer": {