GH-3003: Add link to migration guide

Author: garyrussell

src/reference/asciidoc/whats-new.adoc

@@ -17,29 +17,34 @@ If you are interested in more details, see the Issue Tracker tickets that were r
 
 `Pausable` has been moved from `o.s.i.endpoint` to `o.s.i.core`.
 
+[[x5.2-behavior]]
+=== Behavior Changes
+
+See the https://github.com/spring-projects/spring-integration/wiki/Spring-Integration-5.1-to-5.2-Migration-Guide#dsl-publishsubscribechannel-behavior-change[Migration Guide] about a behavior change when using `publishSubscribeChannel` within a dynamically registered DSL integration flow.
+
 [[x5.2-new-components]]
 === New Components
 
 [[x5.2-rate-limit-advice]]
-=== Rate Limit Advice Support
+==== Rate Limit Advice Support
 
 The `RateLimiterRequestHandlerAdvice` is now available for limiting requests rate on handlers.
 See <<./handler-advice.adoc#rate-limiter-advice,Rate Limiter Advice>> for more information.
 
 [[x5.2-cache-advice]]
-=== Caching Advice Support
+==== Caching Advice Support
 
 The `CacheRequestHandlerAdvice` is now available for caching request results on handlers.
 See <<./handler-advice.adoc#cache-advice,Caching Advice>> for more information.
 
 [[x5.2-kotlin-scripts]]
-=== Kotlin Scripts Support
+==== Kotlin Scripts Support
 
 The JSR223 scripting module now includes a support for Kotlin scripts.
 See <<./scripting.adoc#scripting,Scripting Support>> for more information.
 
 [[x5.2-flux-aggregator]]
-=== Flux Aggregator Support
+==== Flux Aggregator Support
 
 The `FluxAggregatorMessageHandler` is now available for grouping and windowing messages logic based on the Project Reactor `Flux` operators.
 See <<./aggregator.adoc#flux-aggregator,Flux Aggregator>> for more information.