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/decoupling-drupal-vuejs.md

@@ -9,7 +9,8 @@ speakerdeck:
   url: https://speakerdeck.com/opdavies/decoupling-drupal-with-vue-dot-js
 
 events:
-  - name: Blue Conf 2019
+  -
+    name: Blue Conf 2019
     location: Cardiff, UK
     url: https://blueconf.co.uk
     date: 2019-06-07