Add missing prism.js to the documentation of normalize-whitespace
diff --git a/plugins/normalize-whitespace/demo.html b/plugins/normalize-whitespace/demo.html
index 740475c..a6bcf22 100644
--- a/plugins/normalize-whitespace/demo.html
+++ b/plugins/normalize-whitespace/demo.html
@@ -18,6 +18,8 @@
</pre>
</section>
+
+<script src="prism.js"></script>
<script src="plugins/normalize-whitespace/prism-normalize-whitespace.js"></script>
<script type="text/javascript">
// Optional