Fix doc links: use absolute GitHub URLs for npm compatibility

Relative links to docs/ break on npmjs.com. Using absolute GitHub
URLs so links work on both npm and GitHub.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: baixianger

README.md

@@ -31,7 +31,7 @@ A CLI that wraps [Xueqiu (雪球)](https://xueqiu.com) APIs into JSON for AI age
 npm install -g snowball-cli     # or: bun add -g snowball-cli
 ```
 
-> **VPS / Docker / OpenClaw?** See the [Setup Guide](docs/setup.md).
+> **VPS / Docker / OpenClaw?** See the [Setup Guide](https://github.com/baixianger/snowball-cli/blob/main/docs/setup.md).
 
 ## Quick start
 

README.zh-CN.md

@@ -31,7 +31,7 @@
 npm install -g snowball-cli     # 或：bun add -g snowball-cli
 ```
 
-> **VPS / Docker / OpenClaw？** 请看 [安装与授权指南](docs/setup.zh-CN.md)。
+> **VPS / Docker / OpenClaw？** 请看 [安装与授权指南](https://github.com/baixianger/snowball-cli/blob/main/docs/setup.zh-CN.md)。
 
 ## 快速开始
 
@@ -65,7 +65,7 @@ snowball kol SH600519
 
 ## 命令速查
 
-完整命令详解请看 [命令行参考](docs/commands.zh-CN.md)。
+完整命令详解请看 [命令行参考](https://github.com/baixianger/snowball-cli/blob/main/docs/commands.zh-CN.md)。
 
 ### 行情