Update README.md to include comprehensive documentation for ThinkPHP 8, featuring installation instructions, new features, sponsorship details, and links to resources.

app/service.php

@@ -0,0 +1,9 @@
+<?php
+
+use app\AppService;
+
+// 系统服务定义文件
+// 服务在完成全局初始化之后执行
+return [
+    AppService::class,
+];