Markmap-lib example in broken with inline code, fence code and MathJax

[Yukaii]

```markmap
# markmap-lib

## Links

- <https://markmap.js.org/>
- [GitHub](https://github.com/gera2ld/markmap-lib)

## Related

- [coc-markmap](https://github.com/gera2ld/coc-markmap)
- [gatsby-remark-markmap](https://github.com/gera2ld/gatsby-remark-markmap)

## Features

- links
- **inline** ~~text~~ *styles*
- multiline
  text
- `inline code`
-
    ```js
    console.log('code block');
    ```
- MathJax - `\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\)`
```

[Heliopause0916]

The strikethrough syntax seem not to be rendered either.
刪除綫好像也沒有渲染出來
（還有内嵌HTML語法，不過我覺得這是Markmap-lib的鍋，不是CodiMD的）