docs(select): fix maxTagCount api type

[william-xue]

This is a ...

• New feature
• Bug fix
• Site / document update
• Component style update
• TypeScript definition update
• Refactoring
• Code style optimization
• Branch merge
• Other (about what?)

What's the background?

The Select API table currently documents maxTagCount as number only, but the component already supports responsive.

This updates both Chinese and English docs so the API table matches the existing implementation and demo.

Related issue: Closes #8463

API Realization (Optional if not new feature)

• Update components/select/index.zh-CN.md
• Update components/select/index.en-US.md
• Align the documented type with the existing implementation number | 'responsive'

What's the effect? (Optional if not new feature)

• Reduces confusion when using maxTagCount="responsive"
• Keeps the API docs consistent with the current behavior and demo
• No runtime behavior change

Changelog description (Optional if not new feature)

1. docs(select): fix maxTagCount API type in Select docs
2. 文档：修正 Select 中 maxTagCount 的 API 类型说明

Self Check before Merge

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• TypeScript definition is updated/provided or not needed
• Changelog is provided or not needed

Additional Plan? (Optional if not new feature)

No additional plan.