docs: add documentation link to README

Add link to GitHub Pages documentation (https://iflytek.github.io/skillhub/)
under Quick Start section in both English and Chinese README files.

README.md

@@ -65,6 +65,8 @@ firewall, with the same polish you'd expect from a public registry.
 
 ## Quick Start
 
+📖 **[User Documentation →](https://iflytek.github.io/skillhub/)**
+
 Start the full local stack with one of the following commands:
 
 Official images:

README_zh.md

@@ -37,6 +37,8 @@ SkillHub 是一个自托管平台，为团队提供私有的、受治理的智
 
 ## 快速开始
 
+📖 **[用户使用文档 →](https://iflytek.github.io/skillhub/)**
+
 使用以下命令之一启动完整的本地环境：
 
 官方镜像：