docs(web): add document for example

crates/web/examples/hello_world.rs

@@ -1,29 +1,48 @@
+//! Basic example demonstrating how to create a simple web server using micro_web.
+//! This example shows:
+//! - How to define route handlers
+//! - How to set up a router with middleware
+//! - How to configure and start a server
+
 use micro_web::wrapper::DateWrapper;
 use micro_web::router::{get, Router};
 use micro_web::{handler_fn, Server};
 
-
+/// A simple handler that returns "hello world"
 async fn hello_world() -> &'static str {
     "hello world"
 }
 
+/// Default handler for unmatched handlers (404 responses)
+/// 
+/// This handler is called when no other handlers match the incoming request
 async fn default_handler() -> &'static str {
     "404 not found"
 }
 
 #[tokio::main]
 async fn main() {
+    // Create a new router using the builder
     let router = Router::builder()
+        // Add a route that matches GET requests to the root path "/"
+        // handler_fn converts our async function into a handler
         .route("/", get(handler_fn(hello_world)))
+        // Add middleware that will add date headers to responses
         .wrap(DateWrapper)
         .build();
 
+    // Configure and start the server
     Server::builder()
+        // Attach our router to handle incoming requests
         .router(router)
+        // Set the address and port to listen on
         .bind("127.0.0.1:3000")
+        // Set a handler for requests that don't match any routes
         .default_handler(handler_fn(default_handler))
+        // Build the server
         .build()
         .unwrap()
+        // Start the server and wait for it to finish
         .start()
         .await;
 }