Better describe what chef-server-ctl upgrade does
Better describe what chef-server-ctl upgrade does

private chef is not a thing we should ever say again. What does that mean? No customer knows.

Signed-off-by: Tim Smith <764ef62106582a09ed09dfa0b6bff7c05fd7d1e4@chef.io>

chef/chef-server,chef/chef-server,chef/chef-server,chef/chef-server,chef/chef-server,chef/chef-server