Add banner linking labs on Elastic docs landing page

docs/guide/index-custom-title-page.html

@@ -144,6 +144,10 @@ <h4 class="mt-3">
     </ul>
   </div>
 
+  <div style="background-color: #e6f7ff; padding: 15px; border: 1px solid #b8daff; margin: 10px 0; border-radius: 8px; width: 50%;">
+    ℹ️ The <a href="https://github.com/elastic/elasticsearch-labs" style="font-weight: bold; color: #0077cc; text-decoration: none;"> elasticsearch-labs</a> repo contains many interactive Python notebooks for testing out Elasticsearch using the Python client. These examples are mainly focused on vector search, hybrid search and generative AI use cases.
+</div>
+
   <h3 class="explore">Explore by use case</h3>
 
   <div class="row my-4">