Update CHANGELOG-VAADIN8.md (#12563)

* Update CHANGELOG-VAADIN8.md

* Make links work

* Improve wording

* Update CHANGELOG-VAADIN8.md

CHANGELOG-VAADIN8.md

@@ -1,5 +1,13 @@
 # Vaadin 8 extended maintenance version changelog
 
+## Vaadin 8.18.0
+
+* Fixed issue [#12560](https://github.com/vaadin/framework/issues/12560) by improving Grid's horizontal scrolling scrolling logic.
+* Fixed an issue in Combobox where scrolling to selection would fail if the user had typed into the input field. Possibly related to [#12562](https://github.com/vaadin/framework/issues/12562).
+* Added `runAfterRoundTrip` API to the UI class for improved sequence control, allowing execution of a callback after one or more client-server round trips have been completed.
+* Separated portlet support code out of `vaadin-server` into its own package, `vaadin-portlet`. **This will break your build** if your application makes use of Portlet classes and you do not import the `vaadin-portlet` dependency.
+* Added support for Vaadin Multiplatform Runtime version 24+ by adding packages `vaadin-server-mpr-jakarta` and `vaadin-compatibility-server-mpr-jakarta`. This is only needed for MPR 24+, and is ***NOT*** guaranteed to work as generic Jakarta support (even though it does so at the moment) as we may add MPR specific functionality or even hard MPR dependencies in the future.
+
 ## Vaadin 8.17.0
 
 * Improved hierarchical data container handling, resulting in increased speed and correcting some potential memory leaks.
@@ -26,7 +34,7 @@
 ## Vaadin 8.15.2
 
 * Added support for Liferay kernel versions up to 49
-* Changed all resources to use Object.class as interface type to support OSGi Portlets on Liferay CE 7.3.6 GA7 or later (#12504)
+* Changed all resources to use Object.class as interface type to support OSGi Portlets on Liferay CE 7.3.6 GA7 or later ([#12504](https://github.com/vaadin/framework/issues/12504))
 
 ## Vaadin 8.15.1