Adding the section for event call back.

eg:-
- name: example event callback
  description: >
    'Callbacks are actions PDM should take when instructed to do so.

    Some callback types refer to a group of paths and group of properties
    in a similar fashion as the property watch directive.

    The event callback creates the event D-Bus object with the given name
    and the event message.
    eg /xyz/openbmc_project/events/test/<id>'
  class: callback
  callback: event
  paths: example path group
  properties: example property group
  eventName: test
  eventMessage: "Test configuration changed."

When fully implemented, event callbacks will create DBus objects for
preconfigured DBus events.

Change-Id: I73d46a9bc630763cc1a74877803a638f3a8d1e1f
Signed-off-by: Ratan Gupta <ratagupt@in.ibm.com>
diff --git a/src/example/example.yaml b/src/example/example.yaml
index 16cdce8..226f491 100644
--- a/src/example/example.yaml
+++ b/src/example/example.yaml
@@ -99,6 +99,23 @@
       value: testing...
       type: string
 
+- name: example event callback
+  description: >
+    'Callbacks are actions PDM should take when instructed to do so.
+
+    Some callback types refer to a group of paths and group of properties
+    in a similar fashion as the property watch directive.
+
+    The event callback creates the event D-Bus object with the given name
+    and the event message.
+    eg /xyz/openbmc_project/events/test/<id>'
+  class: callback
+  callback: event
+  paths: example path group
+  properties: example property group
+  eventName: test
+  eventMessage: "Test configuration changed."
+
 - name: example method callback
   description: >
     'The method callback invokes the specified D-Bus method.'