Revert ""Order of messages" in STOMP section of reference docs"

This reverts commit dc066b0530 which
wasn't meant to be added to 5.0.x where the feature does not exist.

src/docs/asciidoc/web/websocket.adoc

@@ -1915,59 +1915,6 @@ of the `message-broker` element in XML.
 
 
 
-[[websocket-stomp-ordered-messages]]
-=== Order of Messages
-
-Messages from the broker are published to the "clientOutboundChannel" from where they are
-written to WebSocket sessions. As the channel is backed by a `ThreadPoolExecutor` messages
-are processed in different threads, and the resulting sequence received by the client may
-not match the exact order of publication.
-
-If this is an issue, enable the following flag:
-
-[source,java,indent=0]
-[subs="verbatim,quotes"]
-----
-	@Configuration
-	@EnableWebSocketMessageBroker
-	public class MyConfig implements WebSocketMessageBrokerConfigurer {
-
-		@Override
-		protected void configureMessageBroker(MessageBrokerRegistry registry) {
-			// ...
-			registry.setPreservePublishOrder(true);
-		}
-
-	}
-----
-
-The same in XML:
-
-[source,xml,indent=0]
-[subs="verbatim,quotes,attributes"]
-----
-	<beans xmlns="http://www.springframework.org/schema/beans"
-		xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-		xmlns:websocket="http://www.springframework.org/schema/websocket"
-		xsi:schemaLocation="
-			http://www.springframework.org/schema/beans
-			http://www.springframework.org/schema/beans/spring-beans.xsd
-			http://www.springframework.org/schema/websocket
-			http://www.springframework.org/schema/websocket/spring-websocket.xsd">
-
-		<websocket:message-broker preserve-publish-order="true">
-			<!-- ... -->
-		</websocket:message-broker>
-
-	</beans>
-----
-
-When the flag is set, messages within the same client session are published to the
-"clientOutboundChannel" one at a time, so that the order of publication is guaranteed.
-Note that this incurs a small performance overhead, so enable it only if required.
-
-
-
 [[websocket-stomp-appplication-context-events]]
 === Events