The following is copied from the commit message of `v1.0.0-pdfd_beta1`
from my dotfiles' repo: https://gitlab.com/protesilaos/dotfiles

    PDFD is the book that guides users through the process of setting up
    my custom desktop session.  It also provides information on the
    various aspects of my dotfiles.

    PDFD is meant to use the latest "fixed release" of my dotfiles,
    denoted by tags such as this one.  The repo's contents are copied
    into a separate repository from where PDFD reads from.  That repo is
    called "Code for PDFD (CPDFD)": https://gitlab.com/protesilaos/cpdfd

    PDFD only reads from CPDFD, which in turn only contains tagged
    releases of my dotfiles.