💥 Replace config/private w/ first-class support

The config/private module has been removed. ~/.doom.d (or
~/.config/doom; whichever is detected first) is now a first class
citizen of Doom and should just work(tm).

Your init.el only needs to contain:

  (require 'core (concat user-emacs-directory "core/core"))

And you may place your doom! block in ~/.doom.d/init.el (or
~/.config/doom/init.el).

init.example.el

@@ -147,10 +147,5 @@
        ;; a Spacemacs-inspired keybinding scheme, a custom yasnippet library,
        ;; and additional ex commands for evil-mode. Use it as a reference for
        ;; your own modules.
-       (default +bindings +snippets +evil-commands)
-
-       ;; This allows you to store your private module at
-       ;; $XDG_CONFIG_HOME/doom/. Without +xdg it uses ~/.doom.d/. If your
-       ;; config directory doesn't exist, this module does nothing.
-       (private +xdg))
+       (default +bindings +snippets +evil-commands))