CI: fix deploy on main branch

.github/workflows/main.yml

@@ -23,7 +23,7 @@ jobs:
       - name: build and test
         run: mdbook build && mdbook test
       - name: publish
-        if:   github.event_name == 'push' && github.ref == 'refs/heads/master' && github.repository_owner == 'eunomia-bpf'
+        if:   github.event_name == 'push' && github.ref == 'refs/heads/main' && github.repository_owner == 'eunomia-bpf'
         uses: JamesIves/github-pages-deploy-action@v4.4.1
         with:
           branch: gh-pages

src/24-hide/README.md

@@ -381,6 +381,8 @@ static int handle_event(void *ctx, void *data, size_t data_sz)
 
 完整源代码：<https://github.com/eunomia-bpf/bpf-developer-tutorial/tree/main/src/24-hide>
 
+> 本文所示技术仅为概念验证，仅供学习使用，严禁用于不符合法律法规要求的场景。
+
 ## 编译运行，隐藏 PID
 
 首先，我们需要编译 eBPF 程序：