use the correct method to set the api secret in the oauth api keys ex…

…ample (#92)

docs/programmatic_oauth_example.php

@@ -20,7 +20,7 @@
     ->setClientSecret('clientSecret')             // <-
     ->setTokenStorage($tokenStorage)
     ->setApiKey('apiKey')                         // <- the api credentials found in your
-    ->setApiKey('apiSecret')                      // <- penneo users settings
+    ->setApiSecret('apiSecret')                   // <- penneo users settings
     ->build();
 
 ApiConnector::initializeOAuth($penneoOAuth);