add error to magent2 log code example

Example: mage log magento 2

<?php
  $writer = new \Zend\Log\Writer\Stream(BP . '/var/log/logfile.log');
  $logger = new \Zend\Log\Logger();
  $logger->addWriter($writer);
  $logger->info('Simple Text Log'); // Simple Text Log
  $logger->info('Array Log'.print_r($myArrayVar, true)); // Array Log
?>