Update doc/install/installation.md

Created by: ZKjellberg

Line 295: sudo /etc/init.d/gitlab restart Results in: "Error, unicorn not running!" This is because unicorn is not yet running for first boot. I suggest changing this to 'start'.

Line 305: sudo apt-get install nginx Change command to: sudo apt-get -y install nginx Allowing automated install to simplify and follow pattern of earlier installs.