Improve release notes (Azure#50910)

* Improve release notes

* add doc link

* update

Author: JoshLove-msft

sdk/eventgrid/Azure.Messaging.EventGrid/CHANGELOG.md

@@ -1,17 +1,22 @@
 # Release History
 
-## 5.0.0 (2025-06-25)
+## 5.0.0 (2025-06-26)
 
 ### Features Added
 
 - Added a dependency on the `Azure.Messaging.EventGrid.SystemEvents` package.
-  The system events are now referenced via type-forwarding.
+  The system events are now referenced via [type forwarding](https://learn.microsoft.com/dotnet/standard/assembly/type-forwarding). If you encounter any exceptions
+  related to missing types, ensure that you `dotnet clean` and `dotnet build` your project. You should not
+  use the `Azure.Messaging.EventGrid.SystemEvents` package with a version of `Azure.Messaging.EventGrid` prior to 5.0.0,
+  as it will result in type conflicts.
 
 ### Breaking Changes
 
 - Various system events have been updated to reflect the actual service behavior.
   There are no binary breaks or compilation breaks, but there are behavior breaking changes. For instance,
-  some properties that were previously incorrectly marked as optional, have been marked as required.
+  some properties that were previously incorrectly marked as optional, have been marked as required. If you
+  are using the `EventGridModelFactory` methods to create such events, and you encounter `ArgumentNullException` when
+  upgrading, you will need to update your code to provide the required properties.
 
 ## 5.0.0-beta.1 (2025-06-04)