added drop_all() to example

example/example.cpp

@@ -93,7 +93,7 @@ int main(int, char*[])
         spdlog::set_async_mode(q_size);
         auto async_file = spd::daily_logger_st("async_file_logger", "logs/async_log.txt");
         async_file->info() << "This is async log.." << "Should be very fast!";
-
+        spdlog::drop_all(); //Close all loggers
         //
         // syslog example. linux only..
         //