upgrade node version on ubuntu code example

Example: how to upgrade to latest node in ubuntu 17.04 using terminal

# Using Ubuntu
curl -sL https://deb.nodesource.com/setup_13.x | sudo -E bash -
sudo apt-get install -y nodejs

# Using Debian, as root
curl -sL https://deb.nodesource.com/setup_13.x | bash -
apt-get install -y nodejs