Update README.md

README.md

@@ -398,6 +398,7 @@ void replace_default_logger_example()
 {
     auto new_logger = spdlog::basic_logger_mt("new_default_logger", "logs/new-default-log.txt", true);
     spdlog::set_default_logger(new_logger);
+    spdlog::info("new logger log message");
 }
 ```