Fix comment. Closes #1958.

public/index.php

@@ -53,7 +53,7 @@ $app->run();
 | Shutdown The Application
 |--------------------------------------------------------------------------
 |
-| Once the app has finished running. We will fire off the shutdown events
+| Once the app has finished running, we will fire off the shutdown events
 | so that any final work may be done by the application before we shut
 | down the process. This is the last thing to happen to the request.
 |