Add Scala syntax highlighting

Author: kiendang

_includes/_js-bottom.html

@@ -1,4 +1,5 @@
 <script type="text/javascript" src="{{ '/js/functions.js' | relative_url }}"></script>
 <script src="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.3.1/highlight.min.js"></script>
+<script src="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.3.1/languages/scala.min.js"></script>
 <script>hljs.highlightAll();</script>
 <script src="https://kit.fontawesome.com/a7055d991d.js" crossorigin="anonymous"></script>