update emacs config to 21th century

conf-lisp/rust.el

@@ -0,0 +1,13 @@
+;; *** rust  mode
+(use-package rust-mode
+             :config
+
+             (defun rustlings-done ()
+               "I use this with rustlings"
+               (interactive)
+               (search-backward "DONE")
+               (move-beginning-of-line 1)
+               (kill-line)
+               (save-buffer))
+
+             :mode "\\.rs\\'")