@cmrockwe@umich.edu ,
Yes, it is missing. I didn't find a way to unhide responsive grid. However, we could do from the backend (crx). I guess, a few details are missing from the document as well.
To show responsive grid, go to crxde and the page where the grid is hidden. Each responsive grid has "cq:responsive" node under the "parsys" node. And, this "cq:responsive" node will have a property (cq default behavior) with "hide" value. Just change it to "default".
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Jitendra