Define an alias for behat tests

templates/default.site.yml.twig

 dev:
   root: '/var/www/html/{{ webRoot }}'
   uri: '{{ projectname }}.docker.localhost:8000'
+behat:
+  root: '/var/www/html/{{ webRoot }}'
+  uri: '{{ webserver.type }}'
 live:
   root: '{{ live.root }}'
   uri: '{{ live.uri }}'