Add missing packages to the Emacs configuration [ci-skip]

doc/lisp/build-doc-config.el

@@ -31,6 +31,9 @@
 
 (setq auto-save-default nil)
 
+(use-package tex
+  :ensure auctex)
+
 (use-package org
   :ensure t
   :pin org)
@@ -92,6 +95,9 @@
    (org . t)
    (latex . t )))
 
+(use-package gnuplot
+  :ensure t)
+
 (eval-when-compile
   (require 'easy-mmode)
   (require 'ox))