Disable undo-tree saving

It writes a lot of files which might sound handy but since i don’t always use
Emacs to edit files, they can easily become obsolete.

configuration.org

@@ -1796,7 +1796,9 @@ INFO plist."
 #+begin_src emacs-lisp
 (use-package undo-tree
   :config
-  (global-undo-tree-mode))
+  (global-undo-tree-mode)
+  :custom
+  (undo-tree-auto-save-history nil))
 #+end_src
 
 ** ~ciel~ to mimic ViM’s ~ci~ functionality