Missing usage next links in api-ref

Microversion 2.40 added paging to simple tenant usage, complete with
"next" links, but the api-ref response documentation wasn't updated to
include them.

Change-Id: Iaf2d71cc45b896ccb00271fd455befd24f1efadd
Closes-Bug: #1651254

api-ref/source/os-simple-tenant-usage.inc

@@ -56,8 +56,9 @@ Response
   - server_usages.tenant_id: tenant_id_optional
   - server_usages.uptime: uptime_simple_tenant_usage_optional
   - server_usages.vcpus: vcpus_optional
+  - tenant_usages_links: usage_links
 
-**Example List Tenant Usage For All Tenants: JSON response**
+**Example List Tenant Usage For All Tenants (v2.40): JSON response**
 
 If the ``detailed`` query parameter is not specified or
 is set to other than 1 (e.g. ``detailed=0``), the response is as follows:
@@ -120,8 +121,9 @@ Response
   - total_local_gb_usage: total_local_gb_usage
   - total_memory_mb_usage: total_memory_mb_usage
   - total_vcpus_usage: total_vcpus_usage
+  - tenant_usage_links: usage_links
 
-**Example Show Usage Details For Tenant: JSON response**
+**Example Show Usage Details For Tenant (v2.40): JSON response**
 
 .. literalinclude:: ../../doc/api_samples/os-simple-tenant-usage/v2.40/simple-tenant-usage-get-specific.json
    :language: javascript

api-ref/source/parameters.yaml

@@ -4431,6 +4431,16 @@ url:
   in: body
   required: true
   type: string
+usage_links:
+  description: |
+    Links pertaining to usage. See `API Guide / Links and
+    References
+    <http://developer.openstack.org/api-guide/compute/links_and_references.html>`_
+    for more info.
+  in: body
+  type: array
+  required: false
+  min_version: 2.40
 user_data:
   description: |
     Configuration information or scripts to use upon launch. Must be Base64 encoded.