[TRANSLATION] translate topdown_ustc.md (PKUFlyingPig#283)

* [TRANSLATION] translate topdown_ustc.md

* Update topdown_ustc.en.md

Author: smxm

docs/计算机网络/topdown_ustc.en.md

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+# USTC Computer Networking:A Top-Down Approach
+
+## Descriptions
+
+- Offered by: USTC
+- Instructor: Quan Zheng, Jian Yang
+- Prerequisites: operating system (not required)
+- Programming Languages: None
+- Difficulty: 🌟🌟🌟
+- Class Hour: 40 hours
+
+This course is a well-known computer networking course on the Chinese Internet, it adopts the renowned textbook: _Computer Networking: A Top-Down Approach, 7th Edition_. This a practical course that is not limited to theoretical knowledge, but it is **Strongly recommended** to read the textbook before watching videos, otherwise you _may_ not catch up with the course easily.
+
+
+The course covers the **majority** of the textbook and also **includes** exam content, so enjoy it.
+
+The recordings of the lectures were uploaded by Prof. Zheng himself on Bilibili. Moreover, he has been answering questions in the comments below the videos since 2020, which is very patient and responsible.
+## Resources
+
+- Course Website: <http://staff.ustc.edu.cn/~qzheng/teaching.html>
+- Recordings: <https://www.bilibili.com/video/BV1JV411t7ow/>
+- Slides: <http://staff.ustc.edu.cn/~qzheng/cn.zip>
+- Textbook: _Computer Networking: A Top-Down Approach, 7th Edition_