Adding a categories page to this blog

I succeeded in adding a Categories page to this blog.

Jekyll supports specification of variables category, categories and tags in the front matter of blog posts but it is left as an Exercise for the Reader™ to do anything with them. The Lanyon theme does not itself include page with category or tag lists (but of course is infinitely expandable).

So I created a contents page by adapting this technique with my own amateur CSS applied. The page is contents.html in the root directory of the site and has front matter:

---
layout: page
title: Categories
---

The Lanyon sidebar automatically creates links to any pages with layout: page in the front matter so the Categories page is easily found.