Update node-pool.asciidoc (#1270)

Fix typo in the SimpleNodePool documentation (#1269 )

Author: fgravelaine

docs/node-pool.asciidoc

@@ -45,7 +45,7 @@ use Elastic\Transport\NodePool\Selector\RoundRobin;
 use Elastic\Transport\NodePool\SimpleNodePool;
 
 $nodePool = new SimpleNodePool(
-    new SimpleNodePool(),
+    new RoundRobin(),
     new ElasticsearchResurrect()
 );
 
@@ -69,4 +69,4 @@ You can use the following interfaces for the implementation:
 * https://github.com/elastic/elastic-transport-php/blob/master/src/NodePool/Resurrect/ResurrectInterface.php[ResurrectInterface]
 
 For more information about the Node Pool you can read the
-https://github.com/elastic/elastic-transport-php/blob/master/README.md[elastic-transport-php documentation].
+https://github.com/elastic/elastic-transport-php/blob/master/README.md[elastic-transport-php documentation].