api-ref: Adding backup create response example
The backup create response json file exists but isn't linked
with the api-ref guide.
This patch adds the link to it.
@@ -311,6 +311,11 @@ Response Parameters
- links: links_1
- name: name_1
+Response Example
+----------------
+
+.. literalinclude:: ./samples/backup-create-response.json
+ :language: javascript
Update a backup
~~~~~~~~~~~~~~~
