Tweak the DOI URL and the description

* lisp/emacs-lisp/smie.el: Use a friendlier (HTTPS) DOI URL.  And
fix the year in the description.

lisp/emacs-lisp/smie.el

@@ -56,8 +56,8 @@
 ;; which includes a kind of tutorial to get started with SMIE:
 ;;
 ;;     SMIE: Weakness is Power!  Auto-indentation with incomplete information
-;;     Stefan Monnier, <Programming> Journal 2020, volume 5, issue 1.
-;;     doi: 10.22152/programming-journal.org/2021/5/1
+;;     Stefan Monnier, <Programming> Journal 2021, volume 5, issue 1.
+;;     doi: https://doi.org/10.22152/programming-journal.org/2021/5/1
 
 ;; A good background to understand the development (especially the parts
 ;; building the 2D precedence tables and then computing the precedence levels