Typo in Wiki > Customizing Themes

Some code is duplicated in https://github.com/xz/new.css/wiki/Customizing-Themes/044527198ec26b1b633a06a7c6655ac8840dffd0#usage :

```
<link rel="stylesheet" href="<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@exampledev/new.css@1/new.min.css">">
```