Add api-ref for container stats

This patch adds api-ref for container stats.

Change-Id: I6bdd9973a98983042202b222a2139a03301a8bbb
Partially-Implements: bp zun-api-doc

api-ref/source/containers.inc

@@ -4,7 +4,7 @@
  Manage Containers
 ===================
 
-Lists, creates, shows details for, updates, deletes, starts,
+Lists, creates, shows details for, stats, updates, deletes, starts,
 stops, pauses, unpauses, restarts and renames containers.
 
 Create new container
@@ -244,6 +244,49 @@ This request does not return anything in the response body.
 
   - X-Openstack-Request-Id: request_id
 
+
+Display stats of a container
+============================
+
+.. rest_method:: GET /v1/containers/{container_ident}/stats
+
+Display stats of a container.
+
+Response Codes
+--------------
+
+.. rest_status_code:: success status.yaml
+
+   - 200
+
+.. rest_status_code:: error status.yaml
+
+   - 401
+   - 403
+   - 404
+   - 409
+
+Request
+-------
+
+.. rest_parameters:: parameters.yaml
+
+  - container_ident: container_ident
+
+Response
+--------
+
+.. rest_parameters:: parameters.yaml
+
+  - stats_info: stats_info
+
+Response Example
+----------------
+
+.. literalinclude:: samples/container-stats-resp.json
+   :language: javascript
+
+
 Update information of container
 ===============================
 

api-ref/source/parameters.yaml

@@ -209,6 +209,13 @@ state:
   in: body
   required: true
   type: string
+stats_info:
+  description: |
+    The stats information of a container,
+    including cpu, memory, blk io and net io.
+  in: body
+  required: true
+  type: dict
 status:
   description: |
     The current state of the container.

api-ref/source/samples/container-stats-resp.json

@@ -0,0 +1,9 @@
+{
+    "CONTAINER": "test",
+    "CPU %": 8.89,
+    "MEM USAGE(MiB)": 7,
+    "MEM LIMIT(MiB)": 16048,
+    "MEM %": 0.0436191425723,
+    "BLOCK I/O(B)": "12910592/0",
+    "NET I/O(B)": "246614/648"
+}