IMP: remove unnecessay character

[cisolarix]

There's no need to emphasize that URL is a class. And, this saying is just weird.
没有必要强调 URL 是类。而且这种说法比较奇怪。比如我们一般不会说人王二强

目标章节：例如 1-js/01-getting-started/1-intro

当前上游最新 commit：此处填写本项目英文版 https://github.com/javascript-tutorial/en.javascript.info 的最新 commit，例如 b03ca00

本 PR 所做更改如下：

文件名	参考上游 commit	更改（理由）
article.md	a23882d	修改部分错误

注意，参考上游 commit 是指你所修改的文件，在英文仓库中同名文件的对应 commit，即你此次提交的修改的依据。如果本 PR 你只是提交一个文字或者语句优化，并非根据上游英文仓库的修改而提交的更新，则请填无。

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[leviding]

Thanks!