Update release highlights

Author: swallez

docs/release-notes/release-highlights.asciidoc

@@ -5,6 +5,16 @@ These are the important new features and changes in minor releases. Every releas
 
 For a list of detailed changes, including bug fixes, please see the https://github.com/elastic/elasticsearch-java/releases[GitHub project realease notes].
 
+[discrete]
+==== Version 8.13
+
+* Add an example SpringBoot application - https://github.com/elastic/elasticsearch-java/pull/737[#737]
+
+[discrete]
+==== Version 8.12
+
+* No new feature.
+
 [discrete]
 ==== Version 8.11