Consistent ordering and formatting for talk events

Use a consistent format for talk events, with the most recent talk at
the top of the list with the rest in a descending order.

This removes the need to use a `reverse` filter in the events partial.

source/_talks/about-drupal-association.md

@@ -2,7 +2,8 @@
 title: About the Drupal Association
 description: An impromptu talk about what the Drupal Association is, and what work I’ve been doing since I joined the Association staff.
 events:
-  - name: South Wales Drupal user group (SWDUG)
+  -
+    name: South Wales Drupal user group (SWDUG)
     location: Cardiff, UK
     date: 2014-08-19
 ---