Fix error in sample createSecurityGroup

Author: haphan

samples/networking/v2ext/security_group/create_security_group.php

@@ -21,7 +21,7 @@
 $networkingExtSecGroup = $openstack->networkingV2ExtSecGroups();
 
 /** @var SecurityGroup $securityGroup */
-$securityGroup = $networkingExtSecGroup->createSecurityGroupRule([
+$securityGroup = $networkingExtSecGroup->createSecurityGroup([
     'name' => 'New SecGroup',
     'description' => 'Foo Barrr'
 ]);