fix indentation

Author: mpenet

src/etc/emacs/README.md

@@ -50,7 +50,7 @@ Using MELPA:
 ```lisp
 (require 'package)
 (add-to-list 'package-archives
-    '("melpa" . "http://melpa.milkbox.net/packages/") t)
+             '("melpa" . "http://melpa.milkbox.net/packages/") t)
 (package-initialize)
 ```