Add httpclient5 dependency (#5377)

Add httpclient5 dependency to use Apache HttpClient 5 Transport

Signed-off-by: Gautam Mishra <gautam.mishra@hotmail.com>
Co-authored-by: Naarcha-AWS <97990722+Naarcha-AWS@users.noreply.github.com>

_clients/java.md

@@ -20,6 +20,12 @@ To start using the OpenSearch Java client, you need to provide a transport. The
   <artifactId>opensearch-java</artifactId>
   <version>2.6.0</version>
 </dependency>
+
+<dependency>
+  <groupId>org.apache.httpcomponents.client5</groupId>
+  <artifactId>httpclient5</artifactId>
+  <version>5.2.1</version>
+</dependency>
 ```
 {% include copy.html %}