8.12.0 changelog (#2125)

(cherry picked from commit 57ee5cf)

Author: pquentin

docs/changelog.asciidoc

@@ -1,6 +1,18 @@
 [[changelog-client]]
 == Release notes
 
+[discrete]
+=== 8.12.0
+
+[discrete]
+=== Features
+
+[discrete]
+===== Support for Elasticsearch `v8.12.0`
+
+You can find all the API changes
+https://www.elastic.co/guide/en/elasticsearch/reference/8.12/release-notes-8.12.0.html[here].
+
 [discrete]
 === 8.11.0