Fix: Correct descriptions of clientX and pageX

[yzws1001]

The clientX/Y and pageX/Y descriptions of mouse events are opposite

目标章节：2-ui/3-event-details/1-mouse-events-basics/article.md

当前上游最新 commit：https://github.com/javascript-tutorial/en.javascript.info/commit/34a80e70f8cce5794be259d25f815d7a7db7cbe3

本 PR 所做更改如下：

文件名	参考上游 commit	更改（理由）
article.md	无	修改部分错误

[CLAassistant]

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[javascript-translate-bot]

Please make the requested changes. After it, add a comment "/done".
Then I'll ask for a new review :ghost:

[javascript-translate-bot]

Please make the requested changes. After it, add a comment "/done".
Then I'll ask for a new review :ghost:

[javascript-translate-bot]

Please make the requested changes. After it, add a comment "/done".
Then I'll ask for a new review :ghost:

[javascript-translate-bot]

Please make the requested changes. After it, add a comment "/done".
Then I'll ask for a new review :ghost: