make echo server compile

The original code failed to compile with "expected item after doc comment" error message

README.md

@@ -8,19 +8,21 @@ use std::thread::spawn;
 use tungstenite::server::accept;
 
 /// A WebSocket echo server
-let server = TcpListener::bind("127.0.0.1:9001").unwrap();
-for stream in server.incoming() {
-    spawn (move || {
-        let mut websocket = accept(stream.unwrap()).unwrap();
-        loop {
-            let msg = websocket.read_message().unwrap();
-
-            // We do not want to send back ping/pong messages.
-            if msg.is_binary() || msg.is_text() {
-                websocket.write_message(msg).unwrap();
+fn main () {
+    let server = TcpListener::bind("127.0.0.1:9001").unwrap();
+    for stream in server.incoming() {
+        spawn (move || {
+            let mut websocket = accept(stream.unwrap()).unwrap();
+            loop {
+                let msg = websocket.read_message().unwrap();
+    
+                // We do not want to send back ping/pong messages.
+                if msg.is_binary() || msg.is_text() {
+                    websocket.write_message(msg).unwrap();
+                }
             }
-        }
-    });
+        });
+    }
 }
 ```