It worked like this: rsync2ipfs-cluster fetched the packages from a rsync mirror into an IPFS-MFS-Folder updated the link in IPNS and then added this folder to a running IPFS instance/cluster.
All of those packages are then available for pacman under the (unchanging) IPNS name and the packages themselves are stored in IPFS as usual files.
All you had to was add `http://x86-64.archlinux.pkg.pacman.store.ipns.localhost:8080...` to your mirror list after running your ipfs node (or use a public ipfs gateway).
The website sadly is down now. It had a nicer explanation. None of this still works now however.
EDIT: the folder/list of files was managed by the user hosting the project. The files/packages themselves were distributed. That's just how IPFS/IPNS works. Somebody has to put them into IPFS.
EDIT2: technically the example I posted is a DNSLink which points to a (now gone) TXT record which points to an IPNS name (which is a mutable pointer) that contained the directory of all current archlinux packages.
I hope that was comprehensible.