matching ports in readme and example

README.md

@@ -131,7 +131,7 @@ advertises one in the client well-known, this will not be used.)
 
 ```json
 "livekit": {
-  "livekit_service_url": "http://localhost:8881"
+  "livekit_service_url": "http://localhost:7881"
 },
 ```
 

config/config.sample.json

@@ -5,5 +5,8 @@
       "server_name": "call.ems.host"
     }
   },
+  "livekit": {
+    "livekit_service_url": "http://localhost:7881"
+  },
   "eula": "https://static.element.io/legal/online-EULA.pdf"
 }