Enable feedback with setting in showoff.json

This defaults to not showing the new feedback interface.
We will enable it for trainings after it's been tested more.
Doc update & fix for out of scope variable

Updates the docs to make a note that the feedback bit is optional
I was accessing a variable out of current scope that happened to set to
contents similar to what I was expecting most of the time. Until it
wasn't, then things blew up. So I fixed that.