Add v2 version warning message

Author: crazywhalecc

docs/.vitepress/config.ts

@@ -19,7 +19,7 @@ export default {
             text: 'v3 (alpha)',
             items: [
               { text: 'v3 (alpha)', link: '/en/' },
-              { text: 'v2', link: '/v2/en/guide/' },
+              { text: 'v2', link: 'https://static-php.github.io/v2-docs/' },
             ],
           },
         ],
@@ -43,7 +43,7 @@ export default {
             text: 'v3 (alpha)',
             items: [
               { text: 'v3 (alpha)', link: '/zh/' },
-              { text: 'v2', link: '/v2/zh/guide/' },
+              { text: 'v2', link: 'https://static-php.github.io/v2-docs/' },
             ],
           },
         ],

docs/en/guide/index.md

@@ -1,5 +1,10 @@
 # Guide
 
+::: warning
+You are reading the documentation for StaticPHP v3. The v2 version will be deprecated after the stable release of v3. 
+The 3.0 version is currently in the alpha stage, and you can view the v2 documentation [here](https://static-php.github.io/v2-docs/).
+:::
+
 ## What is StaticPHP?
 
 StaticPHP is a build tool that compiles the PHP interpreter together with any extensions you need into a single self-contained binary. The target system doesn't need PHP or any runtime libraries installed — just copy the binary and run it. Builds target Linux, macOS, and Windows.

docs/zh/guide/index.md

@@ -1,5 +1,10 @@
 # 构建指南
 
+::: warning
+你正在阅读 StaticPHP v3 版本的文档，v2 版本将在 v3 稳定发布后废弃。v3 版本目前仍处于 alpha 阶段，
+你可以在 [这里](https://static-php.github.io/v2-docs/) 查看 v2 文档。
+:::
+
 ## StaticPHP 是什么
 
 StaticPHP 是一个构建工具，能够将 PHP 解释器与你所需的扩展一起编译成一个独立的二进制文件，无需在目标系统上预先安装 PHP 或任何依赖库。