org-id: Fix `org-id-locations' variable name in error message

* lisp/org-id.el (org-id-locations-load): Update error message.

Hi,

While doing some stuff with org-mode, I noticed the error message "Could
not read ‘org-id-values’ from ~/.emacs.d/whatever, setting it to nil".

I quicly understood it’s related to org-id, but the only occurence I
found for ‘org-id-values’ was in that exact error message.

I wonder if this is not a little typo and the error message should speak
of ‘ord-id-locations’ instead?

This patch fix that problem.

I’ve signed the GNU paper to make patch to GNU project if it matters. I can
send a copy of it to anyone if needed.

As this is my first contribution, I hope I do it well.

Have a nice day,

Étienne

Signed-off-by: Étienne Deparis <etienne@depar.is>

lisp/org-id.el

@@ -595,7 +595,7 @@ If SILENT is non-nil, messages are suppressed."
 			(setf (car item) (expand-file-name (car item) loc))))
 		    org-id-locations)))
 	(error
-	 (message "Could not read `org-id-values' from %s, setting it to nil"
+	 (message "Could not read `org-id-locations' from %s, setting it to nil"
 		  org-id-locations-file))))
     (setq org-id-files (mapcar 'car org-id-locations))
     (setq org-id-locations (org-id-alist-to-hash org-id-locations))))