Update git branch on welcome page

Hey,

went through the setup process by following the instructions on the welcome page (http://192.168.44.44/) and encountered a small error.

Under the heading "How to install fresh Drupal 8 version?" you have the code

Win/Mac/Linux host$ vagrant ssh
vagrant guest$ cd ~/sites/drupal8
vagrant guest$ git clone --branch 8.x http://git.drupal.org/project/drupal.git .
vagrant guest$ drush @drupal8 si standard -y

When cloning this will give a warning

warning: Remote branch 8.x not found in upstream origin, using HEAD instead

You should change it too 8.0.x to avoid the warning ( https://groups.drupal.org/node/436178 )