Add two response parameters in the api-ref of getting capabilities

Add "display_name" and "replication_targets" to the response parameters
in the api-ref of getting capabilities.

Change-Id: Id1776641ea9938d024906707fec2e21404668ff7
Closes-bug: #1674237

api-ref/source/v3/capabilities-v3.inc

@@ -39,6 +39,8 @@ 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/v3/parameters.yaml

@@ -601,6 +601,12 @@ 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.
@@ -1473,6 +1479,13 @@ 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
 request_id:
   description: |
     The id of the request during which the message was created.

api-ref/source/v3/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",