8.13 release doc

Author: l-trotta

docs/release-notes/release-highlights.asciidoc

@@ -8,6 +8,7 @@ For a list of detailed changes, including bug fixes, please see the https://gith
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 ==== Version 8.13
 
+* Add ES|QL helpers - https://github.com/elastic/elasticsearch-java/pull/763[#763]
 * Add an example SpringBoot application - https://github.com/elastic/elasticsearch-java/pull/737[#737]
 
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