style(docs): standardize heading formats and numbering

- Enforce Level 1-3 structural numbering based on SUMMARY.md hierarchy
- Remove structural numbering from Level 4+ headings
- Eliminate single child headings by converting to bold text
- Auto-inject summary text for headings with multiple children missing intro text
- Exclude Appendix chapters from structural numbering
- Avoid modifying code block contents
- Add script to detect non-standard English usage in headers

17_security/control_group.md

@@ -1,4 +1,4 @@
-## 控制组
+## 17.2 控制组
 
 控制组是 Linux 容器机制的另外一个关键组件，负责实现资源的审计和限制。