added elpa to readme

Author: gdkrmr

README.md

@@ -48,7 +48,9 @@ Installing from a fresh emacs install
   ```elisp
   (require 'package)
   (add-to-list 'package-archives '("MELPA Stable" . "https://stable.melpa.org/packages/"))
-  (add-to-list 'package-archives '("gnu" . "http://elpa.gnu.org/packages/"))
+  ;; If you want always the latest versions uncomment the following line:
+  ;; (add-to-list 'package-archives '("MELPA" . "https://melpa.org/packages/"))
+  (add-to-list 'package-archives '("gnu" . "https://elpa.gnu.org/packages/"))
   (package-initialize)
   ```