[DOCS] Adds connecting section.

Author: szabosteve

docs/connecting.asciidoc

@@ -0,0 +1,21 @@
+[[connecting]]
+== Connecting
+
+The code snippet below shows how to initialize a low level REST client and the 
+Jackson object mapper to configure an ElasticsearchClient:
+
+```
+// Create the low-level client
+RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
+
+// Create the transport that provides JSON and http services to API clients
+Transport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
+
+// And create our API client
+ElasticsearchClient client = new ElasticsearchClient(transport);
+```
+
+Authentication is managed by the 
+https://www.elastic.co/guide/en/elasticsearch/client/java-rest/current/java-rest-low.html[low-level Rest Client].
+For further details on configuring authentication, refer to the 
+https://www.elastic.co/guide/en/elasticsearch/client/java-rest/current/_basic_authentication.html[documentation].

docs/index.asciidoc

@@ -4,4 +4,5 @@
 include::{asciidoc-dir}/../../shared/attributes.asciidoc[]
 
 include::introduction.asciidoc[]
-include::installation.asciidoc[]
+include::installation.asciidoc[]
+include::connecting.asciidoc[]