[Doc]Add Chinese translation for documentation

[aidoczh]

What this PR does / why we need it?

This PR adds a complete Chinese translation for the documentation using PO files and the gettext toolchain. The goal is to make the documentation more accessible to Chinese-speaking users and help the community grow.

Does this PR introduce any user-facing change?

Yes. This PR introduces Chinese documentation, which users can access alongside the original English documentation. No changes to the core code or APIs.

How was this patch tested?

The translated documentation was built locally using the standard documentation build process (make html or sphinx-build). I checked the generated HTML pages to ensure the Chinese content displays correctly and matches the original structure. No code changes were made, so no additional code tests are required.

vLLM version: v0.9.2
vLLM main: vllm-project/vllm@5780121

---

Please review the translation and let me know if any improvements are needed. I am happy to update the translation based on feedback.

• vLLM version: v0.9.2
• vLLM main: vllm-project/vllm@7ba34b1

[wangxiyuan]

can we add a switch button at index page? https://vllm-ascend.readthedocs.io/en/latest/

[Yikun]

After this PR merged, we need to

1. keep vllm-ascend version
2. add a new vllm-ascend-cn version in readdoc.
3. vllm-ascend add a translations

The we can get something like:
https://vllm-ascend-en-yikun.readthedocs.io/zh-cn/latest/

[Yikun]

BTW, some typos need to be addressed, I will take a deep look soon

[Yikun]

Thanks for contributions, I addressed some nits:

1. fix some typo
2. Add make intl in docs/Makefile
3. remove language = 'en' in conf.py

@aidoczh Would you mind taking a look again?

Preview: https://vllm-ascend-en-yikun.readthedocs.io/en/latest/

[wjjc1017]

Thanks for contributions, I addressed some nits:

1. fix some typo
2. Add make intl in docs/Makefile
3. remove language = 'en' in conf.py

@aidoczh Would you mind taking a look again?

Preview: https://vllm-ascend-en-yikun.readthedocs.io/en/latest/

Points 2 and 3 can be fixed quickly, but point 1 might take a bit more time. I will review these issues and see how to address them systematically.

[Yikun]

@wjjc1017 I already had initial fix for them in this PR. Please feel free to submit new PR in future.

[wangxiyuan]

After this PR merged, once the English doc is changed, what should we do for Chinese version? Developer should update the Chinese at the same time, or is there any sync way?

[aidoczh]

After this PR merged, once the English doc is changed, what should we do for Chinese version? Developer should update the Chinese at the same time, or is there any sync way?

I will monitor new releases of the project. When a new version is released, I will automatically trigger a translation workflow to update the documentation PO files and submit a PR. I will continue to develop and maintain this automated translation workflow in the future.