fix: update skill installation command in README and README.zh.md for consistency

README.md

@@ -56,7 +56,7 @@ links for local decryption.
 Install the bundled skill:
 
 ```bash
-bunx skills add https://github.com/xixu-me/xdrop/tree/main/skills/xdrop
+bunx skills add xixu-me/xdrop
 ```
 
 After that, the agent can use Xdrop from the terminal to:

README.zh.md

@@ -54,7 +54,7 @@ Xdrop 是一款面向人类与智能体的开源端到端加密文件传输应
 安装存储库附带的 skill：
 
 ```bash
-bunx skills add https://github.com/xixu-me/xdrop/tree/main/skills/xdrop
+bunx skills add xixu-me/xdrop
 ```
 
 安装后，智能体可以直接在终端中使用 Xdrop 来：