Fix formatting in proxy configs documentation

Got an error message:

{"error":{"message":"Invalid JSON payload: trailing comma is not allowed: line 8 column 8 (char 141)","type":"invalid_request_error","param":"request_body","code":"400"}}%

docs/my-website/docs/proxy/configs.md

@@ -116,7 +116,7 @@ curl --location 'http://0.0.0.0:4000/chat/completions' \
           "role": "user",
           "content": "what llm are you"
         }
-      ],
+      ]
     }
 '
 ```