Add API documentation for force-delete volume in v2 and v3.

There is no API doc found for force-delete volume in cinder.
We need to add the API doc for the operation with its description,
request and response parameters.

Change-Id: Id25b4070a3946d2d7d89f44bdc81039286a5d8fe
Closes-bug: #1673644

api-ref/source/v2/samples/volume-force-delete-request.json

@@ -0,0 +1,3 @@
+{
+   "os-force_delete": {}
+}

api-ref/source/v2/volumes-v2-volumes-actions.inc

@@ -341,3 +341,31 @@ Request Example
 
 
 
+Force delete volume
+~~~~~~~~~~~~~~~~~~~~~
+
+.. rest_method::  POST /v2/{tenant_id}/volumes/{volume_id}/action
+
+Attempts force-delete of volume, regardless of state. Specify the ``os-force_delete`` action
+in the request body.
+
+
+Normal response codes: 202
+
+
+Request
+-------
+
+.. rest_parameters:: parameters.yaml
+
+   - os-force_delete: os-force_delete
+   - tenant_id: tenant_id
+   - volume_id: volume_id_path
+
+Request Example
+---------------
+
+.. literalinclude:: ./samples/volume-force-delete-request.json
+   :language: javascript
+
+

api-ref/source/v3/samples/volume-force-delete-request.json

@@ -0,0 +1,3 @@
+{
+   "os-force_delete": {}
+}

api-ref/source/v3/volumes-v3-volumes-actions.inc

@@ -338,3 +338,30 @@ Request Example
 
 
 
+Force delete a volume
+~~~~~~~~~~~~~~~~~~~~~
+
+.. rest_method::  POST /v3/{project_id}/volumes/{volume_id}/action
+
+Attempts force-delete of volume, regardless of state. Specify the ``os-force_delete`` action
+in the request body.
+
+
+Normal response codes: 202
+
+
+Request
+-------
+
+.. rest_parameters:: parameters.yaml
+
+   - os-force_delete: os-force_delete
+   - project_id: project_id_path
+   - volume_id: volume_id_path
+
+Request Example
+---------------
+
+.. literalinclude:: ./samples/volume-force-delete-request.json
+   :language: javascript
+