Add X-Auth-Token header in federation examples

cURL examples depicting fetching accessible projects and domains upon
successfull retrieving federated unscoped token should also include
``X-Auth-Token`` header.
This patch adds headers to the examples.

Change-Id: I463e34511b8f9b19012fce955f04a0269d5de9cd
Closes-Bug: #1348680
Merge "Add X-Auth-Token header in federation examples"