WIP: Documentation for Publishing Changes

You don't seem to have a section on editing a unit. I think one is needed prior to a section on discarding changes, as there are some additional quirks to the UI that people may need reassurance about.
- all you have to do is click the pencil to start making changes, or add a component
- you don't have to do anything for Studio to save changes to the draft when you navigate away
- the unit can stay in the "unpublished draft changes made" type state pretty much forever, until you manually publish