[CI] Better CI

The `.export.el' script will export automatically all my blog posts
from `content-org/blog.org' to multiple `.md' files in `content/'.
Manual export is no longer required!

.export.el

@@ -0,0 +1,12 @@
+#!/usr/bin/emacs --script
+(require 'package)
+(add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/") t)
+(package-initialize)
+(package-refresh-contents)
+(package-install 'ox-hugo)
+(require 'ox-hugo)
+(setq org-confirm-babel-evaluate nil
+      org-html-validation-link nil)
+(let* ((file (expand-file-name "content-org/blog.org")))
+  (with-current-buffer (find-file file)
+    (org-hugo-export-wim-to-md t nil nil t)))