Get hash salt from Drupal 8 site in Pantheon using terminus

settings.local.php

  <?php

$databases['default']['default'] = array (
  'database' => '',
  'username' => '',
  'password' => '',
  'host' => 'localhost',
  'port' => '3306',
  'driver' => 'mysql',
  'prefix' => '',
);


// Figure out what your site's hash is by running
// terminus drush d8rtd.dev -- ev 'return getenv("DRUPAL_HASH_SALT")'
$settings['hash_salt']  = 'y-o-u-r--s-i-t-e-s--h-a-s-h--s-a-l-t'