Updating a note removes the title

When I use `hackmd-cli notes update --noteId="XYZ" --content="New content"` to set the contents of a note, the title of the note is removed. Trying to include the title of the note in the content, e.g.

```
hackmd-cli notes update --noteId="XYZ" --content="# My title\nNew content"
```

does not solve the issue: instead, the `# My title` part is included in the content of the note and the title is still empty.

首先追蹤 TypeScript CLI 中的 `notes update` 命令，並了解其內容如何送出以及筆記標題如何處理。重現 issue 中顯示的命令，然後確認更新內容會保留現有標題，同時取代筆記內容。

由索引模型根據 Issue 內容生成。