Added login hint.

views/site/login.php

@@ -26,5 +26,9 @@ $this->params['breadcrumbs'][] = $this->title;
 				</div>
 			<?php ActiveForm::end(); ?>
 		</div>
+		<div class="col-lg-5" style="color:#999;margin:1em;padding-top:60px">
+			You may login with <strong>admin/admin</strong> or <strong>demo/demo</strong>.<br>
+			To modify the username/password, please check out the code <code>app\models\User::$users</code>.
+		</div>
 	</div>
 </div>