Update versions/3.0.3.md

Phil Sturgeon · darrelmiller · web-flow · commit 6f23ae549a30 · 2019-11-27T20:41:57.000Z
Co-Authored-By: Darrel &lt;darrmi@microsoft.com&gt;
diff --git a/versions/3.0.3.md b/versions/3.0.3.md
@@ -1893,7 +1893,7 @@ $response.header.Location | http://example.org/subscription/1
 
 ##### Callback Object Examples
 
-The following example uses the user provided `queryUrl` query string parameter to define the callback URL.
+The following example uses the user provided `queryUrl` query string parameter to define the callback URL.  This is an example of how to use a callback object to describe a WebHook callback that goes with the subscription operation to enable registering for the WebHook.
 
 ```yaml
 myCallback:
