Small correction in examples

Author: bertrandgauthier

examples/01-blog/graphql.php

@@ -1,6 +1,6 @@
 <?php
 // Test this using following command
-// php -S localhost:8080 ./index.php
+// php -S localhost:8080 ./graphql.php
 require_once __DIR__ . '/../../vendor/autoload.php';
 
 use \GraphQL\Examples\Blog\Types;