Load packages associated with tables class option in examples by default

example/mu/example.dtx

@@ -452,6 +452,9 @@
 \usepackage{amsfonts}
 \usepackage{url}      %% Hyperlinks
 \usepackage{markdown} %% Lightweight markup
+\usepackage{tabularx} %% Tables
+\usepackage{tabu}
+\usepackage{booktabs}
 \usepackage{listings} %% Source code highlighting
 \lstset{
   basicstyle      = \ttfamily,