docs(apiDoc): 完善打印相关API文档

[Xavier9896]

本次 Pull Request 更新了 README.md 文件，旨在提升文档的清晰度和组织结构。主要变更包括：将直接打印地址/令牌设置与国际化（i18n）配置的说明分开，并添加了 Electron Hiprint API 文档的链接。

文档结构调整：

• 重新编排了章节内容，明确区分直接打印地址/令牌设置与国际化语言配置，使两项功能的操作指引更直观、更易于遵循。

新增内容：

• 在直接打印客户端章节下添加了 Electron Hiprint API 文档 (apiDoc.md) 的链接，便于快速查阅。

[Copilot]

Pull Request Overview

This PR adds comprehensive API documentation for printing functionality by creating a new apiDoc.md file and updating the README.md structure. The main purpose is to provide clear, organized documentation for both direct client connections and relay server connections.

Key changes include:

• Creation of a detailed API documentation file covering connection methods, client information retrieval, and printing operations
• Reorganization of README.md to separate direct printing configuration from i18n settings
• Addition of a reference link to the new API documentation

Reviewed Changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 2 comments.

File	Description
apiDoc.md	New comprehensive API documentation covering client connections, relay servers, and printing operations
README.md	Restructured sections to separate direct printing setup from i18n configuration and added link to API docs

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