/**
  * Add the PinterestDomainVerifyID field if it is not already set in the config.yml
  * @param FieldList $fields
  */
 public function updateCMSFields(FieldList $fields)
 {
     if (PinterestButton::use_site_config()) {
         $fields->addFieldToTab("Root.Pinterest", TextField::create("PinterestDomainVerifyID", "PinterestDomainVerifyID")->setDescription("Place your pinterest ID here"));
     } else {
         $fields->removeByName("PinterestDomainVerifyID");
     }
 }