[zh] 访问网站时会发生什么？网络运行原理详解

[dethan3]

Checklist:

• I have read freeCodeCamp's contribution guidelines.
• My pull request has a descriptive title (not a vague title like Update index.md)

Closes #539

[miyaliu666]

谢谢 @dethan3 校对这篇文章，我写了一些修改建议，供参考。