docs: add HuggingFace driver documentation

[WUHINS]

Description / 描述

Adds the HuggingFace driver documentation page at pages/guide/drivers/huggingface.md, covering all configuration fields and usage notes.

新增 pages/guide/drivers/huggingface.md，介绍 HuggingFace 驱动的配置字段与使用说明。

The document covers:

• Repo ID / 仓库 ID
• API Token
• Ref / 引用
• Repo Type / 仓库类型
• HF Proxy (download acceleration mirror)
• Root Folder Path / 根目录路径
• Upload Notes: <5MB files use the Commit API, >=5MB files use the Git LFS protocol; uploads respect the configured OpenList proxy
• Default download method flow diagram

Motivation and Context / 背景

The HuggingFace driver was recently added to OpenList but had no user documentation. This PR adds complete bilingual (English / Chinese) docs.

OpenList 近期PR新增了 HuggingFace 驱动，但缺少对应的使用文档。本 PR 补齐了完整的中英双语文档。

Checklist / 检查清单

• I have read the CONTRIBUTING document.
  我已阅读 CONTRIBUTING 文档。
• I have formatted my code or documentation with prettier or other appropriate formatter.
  我已使用 prettier 或其他适当的格式化工具格式化提交的代码或文档。
• I have updated all supported languages (including Chinese and English) for documentation. (If it's needed)
  我已为所有支持语言（包括中文和英文）更新文档内容。 (若适用)
• I have verified that the written documentation or code is properly formatted, with no syntax errors, spelling mistakes.
  我已确认编写的文档或代码格式正确, 无语法错误, 拼写错误。
• I have updated the repository accordingly (If it's needed).
  我已相应更新了相关仓库（若适用）。
  • OpenList #<PR号>