Add a language switcher in README.md file.

[Shawn-Shaw-x]

And create a README_zh_CN.md file that is a Cinnese translation copy of README.md.

Proposed changes

Please include a summary of the changes here and why we need those changes. And also let us know which issue is fixed.

Fixes # <issue_number_here>

---

Types of changes

• [ x ] Documentation Update

---

Please make sure to follow these points

• [ x ] I have read the contributing guidelines.
• [ x ] I have performed a self-review of my own code or work.
• [ x ] My changes generates no new warnings.

---

Screenshots (If Applicable)

---

Other Information

Raise PR again. Make DCO tool happy. Please check! Thank you! @EnriqueL8 @Chengxuan @jimthematrix

[Chengxuan]

@Shawn-Shaw-x Thank you for the first round of the translation. Making a start is always the hardest job. Thanks for doing this heavy-lifting job. I haven't finished all the reviews yet.

A few suggestions so far:

• Let's keep the changes in 'doc-site' folder out of this PR, so this PR can be merged whenever we are happy with the main readme translation. You can raise a separate PR for the doc site translation. Please feel free to contact me if you are not familiar with the process.
• Can you make sure formal title is used 您

please take a look at the suggestions so far and let me know if you have any questions.

[Chengxuan]

LGTM. Thanks for the contribution!

[EnriqueL8]

Thanks @Shawn-Shaw-x and @Chengxuan for the reviews!