Update README to announce upcoming v3 release and project rename

Author: crazywhalecc

README-zh.md

@@ -9,6 +9,11 @@
 
 **StaticPHP** 是一个强大的工具，用于构建可移植的可执行文件，包括 PHP、扩展等。
 
+> [!IMPORTANT]
+> 我们正准备发布 **v3** 版本，届时项目名称将从 **static-php-cli** 更改为 **StaticPHP**。
+> 此分支对应 v3 版本。v2 版本请查看 [v2 分支](https://github.com/crazywhalecc/static-php-cli/tree/main)。
+> 请更新您的参考资料，并关注正式版发布。
+
 ## 特性
 
 - :elephant: 支持多个 PHP 版本 - PHP 8.1, 8.2, 8.3, 8.4, 8.5

README.md

@@ -9,6 +9,11 @@
 
 **StaticPHP** is a powerful tool designed for building portable executables including PHP, extensions, and more.
 
+> [!IMPORTANT]
+> We are preparing to release **v3**, which will include a project rename from **static-php-cli** to **StaticPHP**.
+> And this branch is for v3. For v2, please check the [v2 branch](https://github.com/crazywhalecc/static-php-cli/tree/main).
+> Please update your references and stay tuned for the official release.
+
 ## Features
 
 - :elephant: Support multiple PHP versions - PHP 8.1, 8.2, 8.3, 8.4, 8.5