Add configurable layers in manifest events

Signed-off-by: Andrew Leung <anwleung@gmail.com>

docs/configuration.md

@@ -226,6 +226,8 @@ http:
   http2:
     disabled: false
 notifications:
+  events:
+    manifestlayers: true
   endpoints:
     - name: alistener
       disabled: false
@@ -853,6 +855,8 @@ settings for the registry.
 
 ```none
 notifications:
+  events:
+    manifestlayers: true
   endpoints:
     - name: alistener
       disabled: false
@@ -896,6 +900,13 @@ accept event notifications.
 | `mediatypes`|no| A list of target media types to ignore. Events with these target media types are not published to the endpoint. |
 | `actions`   |no| A list of actions to ignore. Events with these actions are not published to the endpoint. |
 
+### `events`
+
+The `events` structure configures the information provided in event notifications.
+
+| Parameter | Required | Description                                           |
+|-----------|----------|-------------------------------------------------------|
+| `manifestlayers` | no | If `true`, include layer information in manifest events. |
 
 ## `redis`