update vagrant ubuntu 20.04 code example
Example 1: vagrant ubuntu 16.04
vagrant init bento/ubuntu-16.04
vagrant up
Example 2: install vagrant in ubuntu 18.04
curl -O https://releases.hashicorp.com/vagrant/2.2.6/vagrant_2.2.6_x86_64.deb
vagrant init bento/ubuntu-16.04
vagrant up
curl -O https://releases.hashicorp.com/vagrant/2.2.6/vagrant_2.2.6_x86_64.deb