add chinese note in issue template

Author: yyx990803

.github/ISSUE_TEMPLATE.md

@@ -4,4 +4,7 @@ IMPORTANT: Please use the following link to create a new issue:
   https://new-issue.vuejs.org/
 
 If your issue was not created using the app above, it will be closed immediately.
+
+中文用户请注意：
+请使用上面的链接来创建新的 issue。如果不是用上述工具创建的 issue 会被自动关闭。
 -->