Hello, glad to see this moving forward but this documentation makes no sense, the goal of UPM is to separate the dependencies so that they are not pushed to the VCS and easily updatable. Following the procedure linked will not work for that, it just moves the files to the Packages folder, the project will break on any new get from the VCS.
The integration files donāt have to be in the Packages folder, they can be anywhere the UPM can find them as long as the āpackage.jsonā file has been setup.
We donāt have any plans at this point to host the integration online for access from the Unity Package Manager.
Too bad 
Thanks for the information anyway!