[BUG] Private Supermarket berks instructions are wrong

[tas50]

General details

Link to page and section that needs updated:

Product

[ ] Chef Automate
[ ] Chef Habitat
[ ] Chef Infra Client
[ ] Chef Infra Server
[ ] Chef InSpec
[ ] Supermarket

Describe the update that needs to be made. Be as specific as possible:

https://docs.chef.io/install_supermarket/#upload-the-wrapper

This is real confusing. We're telling them to use berks, which is meh, but we're doing it all wrong. Berks install and berks upload will do all you need to do. We're doing some real funky stuff in these steps to upload all the cookbooks when berks install will do that for you.