docs(README_zh-hans): clarify conditions for not using Transformers

[GuaiZai233]

Rephrase section title for clarity regarding the use of Transformers.

What does this PR do?

This PR updates the Chinese README (i18n/README_zh-hans.md) to rephrase a section title for better clarity:

• Before: ## 为什么我不该用 Transformers？
• After: ## 什么情况下我不该用 Transformers？

The new title more accurately conveys that the section discusses appropriate use cases and limitations, rather than sounding like a general discouragement. This helps readers better understand when Transformers might not be the right tool for their specific needs (e.g., if they need low-level control or a generic training loop).

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you read the [contributor guideline]...
• Was this discussed/approved via a Github issue or the [forum]... (optional, can leave unchecked for trivial docs fixes)
• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests? (N/A for docs-only change)

Who can review?

@stevhliu

[stevhliu]

thanks, agree that framing it differently can avoid sounding like a discouragement. we should also update the English source so their headings remain in sync.

how about something like, "When shouldn't I use Transformers"? this way it mirrors the structure of the section before it and it is more situational.

[GuaiZai233]

@stevhliu Done. Thanks for the suggestion!
I've updated both the English and Chinese READMEs to use "When shouldn't I use Transformers?" / "什么情况下我不该用 Transformers?" for better consistency and situational framing.

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[stevhliu]

thanks! 🤗