docs(changelog) clarify new 'consumer' field in logging plugins

From Kong#2384

Signed-off-by: Thibault Charbonnier <[email protected]>

CHANGELOG.md

@@ -29,7 +29,9 @@
     upstream services. Thanks [Paul Austin](https://github.com/pauldaustin)
     for the contribution.
     [#2051](https://github.com/Mashape/kong/pull/2051)
-  - logging: Logging plugins now also log the `custom_id` or `username` of authenticated Consumers.
+  - Logging plugins: The produced logs now include a `consumer` field,
+    which contains the properties of the authenticated Consumer
+    (`id`, `custom_id`, and `username`), if any.
     [#2367](https://github.com/Mashape/kong/pull/2367)
 
 ### Fixed