Some mistakes about 05-basic-dom-node-properties/2-tree-info

[en.javascript.info](https://github.com/javascript-tutorial/en.javascript.info)/[2-ui](https://github.com/javascript-tutorial/en.javascript.info/tree/master/2-ui)/[1-document](https://github.com/javascript-tutorial/en.javascript.info/tree/master/2-ui/1-document)/[05-basic-dom-node-properties](https://github.com/javascript-tutorial/en.javascript.info/tree/master/2-ui/1-document/05-basic-dom-node-properties/2-tree-info/)

1. Rename 2-tree-info to 1-tree-info

Reason: 2-tree-info is first task

2. Using external js instead of inline js

Reason: js will execute before brower finish HTML loading. It's inconvenient for user to count \

從 2-ui/1-document/05-basic-dom-node-properties/2-tree-info 開始，檢查任務檔案及其中的 inline JavaScript。確認目錄編號以及範例目前載入 JavaScript 的方式；完成的標準是任務使用所要求的名稱，且其 JavaScript 在外部載入而不會干擾練習。

由索引模型根據 Issue 內容生成。