update readme with test instructions
update readme with test instructions

Signed-off-by: Christoph Hartmann <711c73f64afdce07b7e38039a96d2224209e9a6c@lollyrock.com>
patcon/chef-ssh-hardening,michaelklishin/chef-ssh-hardening,dev-sec/chef-ssh-hardening,hardening-io/chef-ssh-hardening,dev-sec/chef-ssh-hardening,patcon/chef-ssh-hardening,hardening-io/chef-ssh-hardening,IFTTT/chef-ssh-hardening,michaelklishin/chef-ssh-hardening,IFTTT/chef-ssh-hardening