message: Make a reference to default vs site's drush.
diff: # Drush 9
  +Lagoon defaults to Drush 8. Drush 9 is used if you install Drush 9 into your Drupal site via Composer.
  +
  +## Aliases
  +
  Unfortunately Drush 9 does not provide the possibility to inject dynamic Site Aliases like Drush 8 did. We are working with the Drush team to implement this again. In the meantime we have a workaround that allows you to use Drush 9 with Lagoon.
  ### Basic Idea
  