Add 'replication_targets' and 'display_name' in API docs

'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

api-ref/source/v2/capabilities-v2.inc

@@ -40,6 +40,8 @@ Response Parameters
    - vendor_name: vendor_name
    - properties: properties
    - storage_protocol: storage_protocol
+   - replication_targets: replication_targets
+   - display_name: display_name
 
 Response Example
 ----------------

api-ref/source/v2/parameters.yaml

@@ -471,6 +471,12 @@ description_9:
   in: body
   required: true
   type: string
+display_name:
+  description: |
+    The name of volume backend capabilities.
+  in: body
+  required: true
+  type: string
 driver_version:
   description: |
     The driver version.
@@ -1216,6 +1222,13 @@ replication_status:
   in: body
   required: true
   type: string
+replication_targets:
+  description: |
+    A list of volume backends used to replicate volumes
+    on this backend.
+  in: body
+  required: true
+  type: list
 reserved:
   description: |
     Reserved volume size. Visible only if you set the

api-ref/source/v2/samples/backend-capabilities-response.json

@@ -8,6 +8,7 @@
     "display_name": "Capabilities of Cinder LVM driver",
     "description": "These are volume type options provided by Cinder LVM driver, blah, blah.",
     "visibility": "public",
+    "replication_targets": [],
     "properties": {
         "compression": {
             "title": "Compression",