config: update security link to underyling library

Docs/readme changed in the meantime

Author: mfn

src/config/config.php

@@ -199,7 +199,7 @@
 
     /*
      * Options to limit the query complexity and depth. See the doc
-     * @ https://github.com/webonyx/graphql-php#security
+     * @ http://webonyx.github.io/graphql-php/security/
      * for details. Disabled by default.
      */
     'security' => [