Revive project "k3x" or remove reference

[Silvanoc]

Currently the Readme is referring to the project "k3x" as a related project. But "k3s" appears to be abandoned since it got its last commit almost 2 years ago and it has an obsolete dependency.#

I'd therefore consider either reviving that project (either by that -k3x- community of by this -k3d- community) or removing the reference from the Readme.