Revise README for Linux SSH Init Script

Updated README to enhance clarity and provide detailed features.

README.md

@@ -1,2 +1,41 @@
-# linux-ssh-init-sh
-POSIX-compliant Linux server initialization & SSH hardening script. (Debian/Ubuntu/CentOS/Alpine) | Linux 服务器初始化与 SSH 安全加固脚本（一键配置密钥、端口、BBR）。
+# Linux Server Init & SSH Hardening Script (linux-ssh-init-sh)
+
+<p align="center">
+  <img src="https://img.shields.io/badge/Shell-POSIX_sh-blue?style=flat-square" alt="POSIX Shell">
+  <img src="https://img.shields.io/badge/License-MIT-green?style=flat-square" alt="License">
+  <img src="https://img.shields.io/github/v/release/247like/linux-ssh-init-sh?style=flat-square" alt="Release">
+</p>
+
+<p align="center">
+  <strong>
+    <a href="#-english">📖 English</a> | <a href="#-中文文档">📖 中文文档</a>
+  </strong>
+</p>
+
+---
+
+<div id="-english"></div>
+
+## 📖 English
+
+A production-ready, POSIX-compliant shell script designed to initialize Linux servers and harden SSH security in minutes.
+
+### ✨ Key Features
+
+* **Universal Compatibility**: Works flawlessly on **Debian 10/11/12**, **Ubuntu**, **CentOS 7/8/9**, **Alma/Rocky**, and **Alpine Linux**.
+* **POSIX Compliant**: Written in pure `/bin/sh`. No `bash` dependency.
+* **Safety Architecture**:
+    * **Managed Config Block**: Inserts configuration at the **top** of `sshd_config` to strictly override vendor defaults (bypasses the Debian 12 `Include` trap).
+    * **Anti-Lockout**: Smart fallback mechanisms to prevent locking yourself out (see *Strict Mode* below).
+    * **Firewall Awareness**: Automatically configures `ufw` or `firewalld` when changing ports.
+* **Automation**:
+    * **SSH Keys**: Imports from GitHub/URL/Paste.
+    * **Random Port**: Generates valid random high ports (20000-60000).
+    * **Optimization**: One-click System Update & TCP BBR.
+
+### 🚀 Quick Start
+
+Run as **root**:
+
+```bash
+curl -fsSL [https://raw.githubusercontent.com/247like/linux-ssh-init-sh/main/init.sh](https://raw.githubusercontent.com/247like/linux-ssh-init-sh/main/init.sh) -o init.sh && chmod +x init.sh && ./init.sh