[DOCS] Bump copyright to 2019 for Java HLRC license (#50206)

docs/java-rest/license.asciidoc

@@ -1,6 +1,6 @@
 == License
 
-Copyright 2013-2018 Elasticsearch
+Copyright 2013-2019 Elasticsearch
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.