refactor: deprecate doom-etc-dir for doom-data-dir

doom-etc-dir will be renamed to doom-data-dir, to better reflect its
purpose, and align it with XDG_DATA_HOME (where it will be moved to in
v3, where Doom will begin to obey XDG directory conventions more
closely).

lisp/doom-cli.el

@@ -108,7 +108,7 @@
 ;; Create all our core directories to quell file errors.
 (mapc (doom-rpartial #'make-directory 'parents)
       (list doom-local-dir
-            doom-etc-dir
+            doom-data-dir
             doom-cache-dir))
 
 ;; Load standard :help and :version handlers.

lisp/doom-editor.el

@@ -291,7 +291,7 @@ tell you about it. Very annoying. This prevents that."
 
 
 ;;;###package bookmark
-(setq bookmark-default-file (concat doom-etc-dir "bookmarks"))
+(setq bookmark-default-file (concat doom-data-dir "bookmarks"))
 
 
 (use-package! recentf

lisp/doom.el

@@ -230,9 +230,9 @@ downloaded/installed by packages. Must end in a slash.")
 Use this as a storage location for this system's installation of Doom Emacs.
 
 These files should not be shared across systems. By default, it is used by
-`doom-etc-dir' and `doom-cache-dir'. Must end with a slash.")
+`doom-data-dir' and `doom-cache-dir'. Must end with a slash.")
 
-(defconst doom-etc-dir
+(defconst doom-data-dir
   (if doom-profile
       doom-profile-data-dir
     (concat doom-local-dir "etc/"))
@@ -274,6 +274,7 @@ users).")
 ;;; Legacy support
 
 (define-obsolete-variable-alias 'doom-private-dir 'doom-user-dir "3.0.0")
+(define-obsolete-variable-alias 'doom-etc-dir 'doom-data-dir "3.0.0")
 
 (make-obsolete-variable 'EMACS28+   "Use (>= emacs-major-version 28) instead" "3.0.0")
 (make-obsolete-variable 'EMACS29+   "Use (>= emacs-major-version 29) instead" "3.0.0")
@@ -351,7 +352,7 @@ users).")
 ;; By default, Emacs stores `authinfo' in $HOME and in plain-text. Let's not do
 ;; that, mkay? This file stores usernames, passwords, and other treasures for
 ;; the aspiring malicious third party. You'll need a GPG setup though.
-(setq auth-sources (list (concat doom-etc-dir "authinfo.gpg")
+(setq auth-sources (list (concat doom-data-dir "authinfo.gpg")
                          "~/.authinfo.gpg"))
 
 (define-advice en/disable-command (:around (fn &rest args) write-to-data-dir)

lisp/lib/sandbox.el

@@ -63,9 +63,9 @@
           (setq init-file-debug t
                 doom-emacs-dir ,doom-emacs-dir
                 doom-cache-dir ,(expand-file-name "cache/" doom-sandbox-dir)
-                doom-etc-dir   ,(expand-file-name "etc/" doom-sandbox-dir))
+                doom-data-dir  ,(expand-file-name "data/" doom-sandbox-dir))
           (defun doom--write-to-etc-dir-a (fn &rest args)
-            (let ((user-emacs-directory doom-etc-dir))
+            (let ((user-emacs-directory doom-data-dir))
               (apply fn args)))
           (advice-add #'locate-user-emacs-file :around #'doom--write-to-etc-dir-a)
           ;; emacs essential variables

lisp/lib/scratch.el

@@ -5,7 +5,7 @@
 
 Will be saved in `doom-scratch-dir'.")
 
-(defvar doom-scratch-dir (concat doom-etc-dir "scratch")
+(defvar doom-scratch-dir (concat doom-data-dir "scratch")
   "Where to save persistent scratch buffers.")
 
 (defvar doom-scratch-initial-major-mode nil

lisp/lib/store.el

@@ -3,7 +3,7 @@
 ;; This little library abstracts the process of writing arbitrary elisp values
 ;; to a 2-tiered file store (in `doom-store-dir'/`doom-store-location').
 
-(defvar doom-store-dir (concat doom-etc-dir "store/")
+(defvar doom-store-dir (concat doom-data-dir "store/")
   "Directory to look for and store data accessed through this API.")
 
 (defvar doom-store-persist-alist ()