Adapt release notes for Elasticsearch v9

Closes gh-46526

Author: snicoll

platform/spring-boot-dependencies/build.gradle

@@ -377,7 +377,8 @@ bom {
 			]
 		}
 		links {
-			releaseNotes("https://www.elastic.co/guide/en/elasticsearch/reference/current/release-notes-{version}.html")
+			releaseNotes(version -> "https://www.elastic.co/docs/release-notes/elasticsearch/clients/java/%s"
+					.formatted(version.toString("-")))
 			javadoc("elasticsearch-rest-client", version -> "https://artifacts.elastic.co/javadoc/org/elasticsearch/client/elasticsearch-rest-client/%s".formatted(version), "org.elasticsearch.client")
 			javadoc("elasticsearch-java", version -> "https://artifacts.elastic.co/javadoc/co/elastic/clients/elasticsearch-java/%s".formatted(version), "co.elastic.clients.elasticsearch", "co.elastic.clients.transport")
 			javadoc("elasticsearch-rest-client-sniffer", version -> "https://artifacts.elastic.co/javadoc/org/elasticsearch/client/elasticsearch-rest-client-sniffer/%s".formatted(version), "org.elasticsearch.client.sniff")