php: fix examples ClientStub constructor
diff --git a/examples/php/greeter_client.php b/examples/php/greeter_client.php
index e5e4c26..718ef88 100644
--- a/examples/php/greeter_client.php
+++ b/examples/php/greeter_client.php
@@ -36,7 +36,9 @@
 require dirname(__FILE__) . '/helloworld.php';
 
 function greet($name) {
-  $client = new helloworld\GreeterClient('localhost:50051', []);
+  $client = new helloworld\GreeterClient('localhost:50051', [
+    'credentials' => Grpc\ChannelCredentials::createInsecure()
+  ]);
   $request = new helloworld\HelloRequest();
   $request->setName($name);
   list($reply, $status) = $client->SayHello($request)->wait();