chore(docs): Apply #6822 (playground definition) to the rest of CONTRIBUTING files (#6824)

* Added playground definition

Added a small definition about programming/coding playgrounds for making it understandable to beginners

* Define what is a playground

Via / completes:
- What's a programming playground? #6107
- Added playground definition #6817
- Sentence added under playground #6819

Thanks @Suman373 for the initial idea.

Co-authored-by: Suman Roy <95040233+Suman373@users.noreply.github.com>

* reword playground definition as suggested

Co-authored-by: Eric Hellman <eric@hellman.net>

* copy #6822 playground definition into rest files

* translate #6822 (playground definition) to spanish

* translate #6822 (playground definition) to italian

Co-authored-by: ImVector <59611597+LuigiImVector@users.noreply.github.com>

* translate #6822 (playground definition) to french

Thanks to @Existential-nonce

Co-authored-by: nonce <77142078+Existential-nonce@users.noreply.github.com>

* translate EbookFoundation#6822 (playground definition) to chinese

Provided by @kang8. Thank you too much!

Co-authored-by: kang <1115610574@qq.com>

* Improve playground definition in `zh_TW` language

Co-authored-by: Alan Syue <33183531+AlanSyue@users.noreply.github.com>

* Minor improve playground definition in `fr` language

Co-authored-by: lorrding <mathias.berthonneau@gmail.com>

Co-authored-by: Suman Roy <95040233+Suman373@users.noreply.github.com>
Co-authored-by: Eric Hellman <eric@hellman.net>
Co-authored-by: ImVector <59611597+LuigiImVector@users.noreply.github.com>
Co-authored-by: nonce <77142078+Existential-nonce@users.noreply.github.com>
Co-authored-by: kang <1115610574@qq.com>
Co-authored-by: Alan Syue <33183531+AlanSyue@users.noreply.github.com>
Co-authored-by: lorrding <mathias.berthonneau@gmail.com>

docs/CONTRIBUTING-zh.md

@@ -18,11 +18,12 @@
 2. 你不需要会 Git：如果你发现了一些有趣的东西 *尚未出现在本仓库* 中，请开一个[Issue](https://github.com/EbookFoundation/free-programming-books/issues)进行主题讨论。
     * 如果你已经知晓Git，请Fork本仓库并提交Pull Request (PR)。
 
-3. 这里有5种列表，请选择正确的一个：
+3. 这里有6种列表，请选择正确的一个：
 
     * *Books* ：PDF、HTML、ePub、基于一个 gitbook.io的站点、一个Git仓库等等。
     * *Courses* ：课程是一种学习材料，而不是一本书 [This is a course](http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-006-introduction-to-algorithms-fall-2011/)。
     * *Interactive Tutorials* ：一个交互式网站，它允许用户输入代码或命令并对结果进行评估。例如：[Try Haskell](http://tryhaskell.org)，[Try GitHub](http://try.github.io)。
+    * *Playgrounds* : Playgrounds 可能是学习编程的在线交互式网站、游戏或桌面软件。你可以在上面编写、编译、运行或分享代码片段。Playgrounds 通常允许你 fork 代码然后在其中尽情的编写代码。
     * *Podcasts and Screencasts* ：播客和视频。
     * *Problem Sets & Competitive Programming* ：一个网站或软件，让你通过解决简单或复杂的问题来评估你的编程技能，有或没有代码审查，有或没有与其他用户对比结果。