Fix example in Javadoc for @EnableWebSocket

The `echoWebSocketHandler()` method is not defined in the
`WebSocketConfigurer` interface and should therefore be annotated with
`@Bean` instead of `@Override`.

Closes gh-30187

spring-websocket/src/main/java/org/springframework/web/socket/config/annotation/EnableWebSocket.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -49,7 +49,7 @@
  *         registry.addHandler(echoWebSocketHandler(), "/echo").withSockJS();
  * 	   }
  *
- *	   @Override
+ *	   @Bean
  *	   public WebSocketHandler echoWebSocketHandler() {
  *         return new EchoWebSocketHandler();
  *     }