[DOCS] Temporarily redirect getting started button link on landing page. (#623) (#624)

Co-authored-by: István Zoltán Szabó <[email protected]>

Author: github-actions[bot]

docs/index-custom-title-page.html

@@ -63,7 +63,7 @@ <h2>Documentation</h2>
         The Java API client provides strongly typed requests and responses for all Elasticsearch APIs.
       </p>
       <p>
-        <a href="https://www.elastic.co/guide/en/elasticsearch/client/java-api-client/current/_getting_started.html">
+        <a href="https://www.elastic.co/guide/en/elasticsearch/client/java-api-client/current/introduction.html">
           <button class="btn btn-primary">Get started</button>
         </a>
       </p>