Add English version of README for One-Handed Keyboard project

[lalithaar]

Added detailed documentation for the One-Handed Keyboard project, including build guides, hardware specifications, and assembly instructions.

Starting with readme translation for #10, if this style is okay - I would love to translate other parts too :>

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添加了单手键盘项目的详细文档，包括构建指南、硬件规格和组装说明。

首先从 #10 的 readme 翻译开始，如果这种风格没问题的话，我也很乐意翻译其他部分 :>

[LarsArtmann]

It would be nice too have a English README.md too :)

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要是能有个英文版的README.md就更好了 :)

[HamzaETTH]

I think it might be better if both versions are integrated into the main README.md, so visitors can see everything by clicking on a quick navigation link at the top, for example:

## 🌐 Language / 语言
- [English](#english-version)
- [中文](#中文版本)

Alternatively, maybe keep this version separate as you’ve done, but add a relative link on the very top of the main README so people can easily find it.