It looks like this page is designed for people who already know what an "uplift" is, but wish to implement it properly. That being said, it also appears that "uplifts" will include bug fixes made in Tor Browser and sent upstream to Firefox, rather than just features added (but disabled by default) as was implied in the OP article. I would have assumed that bug fixes made in a downstream product would already have a mechanism to find their way to Firefox. Maybe "uplift" was the term all along for that mechanism, or is a rebranding of it?