Address code review comments

Signed-off-by: Andriy Redko <andriy.redko@aiven.io>

USER_GUIDE.md

@@ -76,7 +76,13 @@ There are multiple low level transports which `OpenSearchClient` could be config
 ### Create a client using `RestClientTransport`
 
 ```java
-//Initialize the client with SSL and TLS enabled
+import org.apache.http.HttpHost;
+
+final HttpHost[] hosts = new HttpHost[] {
+    new HttpHost("localhost", 9200, "http")
+  };
+
+// Initialize the client with SSL and TLS enabled
 final RestClient restClient = RestClient
   .builder(hosts).
   .build();
@@ -98,6 +104,12 @@ Upcoming OpenSearch `3.0.0` release brings HTTP/2 support and as such, the `Rest
 ### Create a client using `ApacheHttpClient5Transport`
 
 ```java
+import org.apache.hc.core5.http.HttpHost;
+
+final HttpHost[] hosts = new HttpHost[] {
+    new HttpHost("localhost", "http", 9200)
+  };
+
 final OpenSearchTransport transport = ApacheHttpClient5TransportBuilder
     .builder(hosts)
     .setMapper(new JacksonJsonpMapper())