Update API Key reference in knowledge-base.md

[jdjfjdsfj]

Modifications / 改动点

修正了错误的模型提供商，更改了文档中knowledge-base.md

• This is NOT a breaking change. / 这不是一个破坏性变更。

Screenshots or Test Results / 运行截图或测试结果

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Checklist / 检查清单

• 😊 If there are new features added in the PR, I have discussed it with the authors through issues/emails, etc.
  / 如果 PR 中有新加入的功能，已经通过 Issue / 邮件等方式和作者讨论过。

• 👀 My changes have been well-tested, and "Verification Steps" and "Screenshots" have been provided above.
  / 我的更改经过了良好的测试，并已在上方提供了“验证步骤”和“运行截图”。

• 🤓 I have ensured that no new dependencies are introduced, OR if new dependencies are introduced, they have been added to the appropriate locations in requirements.txt and pyproject.toml.
  / 我确保没有引入新依赖库，或者引入了新依赖库的同时将其添加到 requirements.txt 和 pyproject.toml 文件相应位置。

• 😮 My changes do not introduce malicious code.
  / 我的更改没有引入恶意代码。

Summary by Sourcery

Documentation:

• Correct the referenced API key provider name in docs/zh/use/knowledge-base.md for the OpenAI Embedding configuration.

[sourcery-ai]

Hey - I've reviewed your changes and they look great!

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[gemini-code-assist]

Code Review

This pull request updates the documentation to correctly identify SiliconFlow as the API Key provider for the knowledge base setup. The review feedback suggests improving Chinese typography by removing spaces around the brand name and correcting a numbering sequence error in the list where the steps skip from 2 to 5.