[emacs] add Borg's layer/essentials init, with some of my stuff

[~bandali/configs] / Makefile

-include lib/borg/borg.mk

bootstrap-borg:
        @git submodule--helper clone --name borg --path lib/borg \
        --url git@github.com:emacscollective/borg.git
        @cd lib/borg; git symbolic-ref HEAD refs/heads/master
        @cd lib/borg; git reset --hard HEAD