Hi @RobertHerron ...
Yeah...that's correct. You'll create the rubric in Excel following the examples that James has provided, then you'll copy/paste those cells into a text box that James' script creates inside of Canvas. It will automatically create the rubric for you. It's pretty slick, and like I said, it has saved me tons of time creating rubric lines one by one.
On a side note, Instructure is working on a rubric redesign, and I wanted to provide you with a couple links. In the first link, you'll see in Phase 2 of their project that importing rubrics is something that they will be working on for everyone. So, it may be that James' script becomes obsolete at some point.
I hope this is helpful for you!