update example

example/example.cpp

@@ -113,9 +113,7 @@ void async_example()
     for (int i = 0; i < 100; ++i)
     {
         async_file->info("Async message #{}", i + 1);
-    }
+    }	
-	// you can wait for all the messages to processed:
-	// spdlog::thread_pool()->wait_empty();
 }
 
 // syslog example (linux/osx/freebsd)