'replication_targets' is always returned in Response of GET/v2/
{tenant_id}/capabilities/{hostname} API, but it is not written
in either Response parameters table or JSON example.
'display_name' is listed in JSON example but not described in
Response parameter table.
This patch adds the above two missing information.
Change-Id: Ib3bf54df7c5c400cfec64dd9c7df136c87cd6376
Closes-Bug: #1603306
8efbf756a3