clarification needed for upgrading automate for marketplace images

[ericcalabretta]

https://docs.chef.io/azure_portal.html

clarification is needed for upgrading automate for marketplace images.

Better instructions are needed for upgrading Chef-Automate and Chef-Server when using a marketplace image. The current instructions only list for chef-server and only in the context of migrating to azure.

The command to upgrade Automate is "chef-marketplace-ctl upgrade --automate " but is not listed