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/introduction-to-mob-programming.md

@@ -7,7 +7,8 @@ speakerdeck:
   ratio: '1.77725118483412'
   url: https://speakerdeck.com/opdavies/an-introduction-to-mob-programming
 events:
-  - name: PHP South Wales
+  -
+    name: PHP South Wales
     location: Cardiff, Wales
     date: '2022-09-28'
     url: https://www.meetup.com/php-south-wales/events/288359737