“slotted” 拼写错误

[Allen-su]

目标章节：8-web-components/6-shadow-dom-style

当前上游最新 commit：5a17a97

本 PR 所做更改如下：

文件名	参考上游 commit	更改（理由）
article.md	无	::slotted 拼写错误，写成了 “sloated”

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[xuesongde]

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