Removed From prepare.md ppa:ubuntu-lxc/lxd-stable reference since is deprecated
Removed the instruction that adds the ppa for lxd-stable, since the is deprecated. For what i've search the maintainers recommend to use the backport system or install as a snap. More information: https://github.com/lxc/lxd/issues/4176
Edited by Toon Claes