Find a place for "Upgrade Tests" tutorial
Created by: seancolsen
TL;DR: Grab the content from Upgrade Tests and find a home for it in the Dev Guide.
Longer story: I'm migrating docs content out of the buildkit repo and into the Dev Guide and as part of this process I'm deleting that file which contains a mix of content that needs some work to be well-incorporated into the Dev Guide. I'm using issues to track the process of this migration, section-by-section, since I think the content will likely need to go to multiple places.