Add v3 api-ref for showing encryption specs item

This patch adds v3 api-ref for showing encryption specs item for an
existing volume type.

Change-Id: I80b1853cbe2cc02a056195e967e9422617bbf850

api-ref/source/v3/parameters.yaml

@@ -113,6 +113,12 @@ key_4:
   in: path
   required: true
   type: string
+key_5:
+  description: |
+    The key name of the encryption spec for a volume type.
+  in: path
+  required: true
+  type: string
 message_id:
   description: |
     The UUID of the message.

api-ref/source/v3/samples/encryption-type-specific-specs-show-response.json

@@ -0,0 +1,3 @@
+{
+    "cipher": "aes-xts-plain64"
+}

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

@@ -385,7 +385,7 @@ Response Example
    :language: javascript
 
 Show an encryption type
-~~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~
 
 .. rest_method::  GET /v3/{project_id}/types/{volume_type_id}/encryption
 
@@ -429,9 +429,35 @@ Response Example
    :language: javascript
 
 
-Delete an encryption type
+Show encryption specs item
 ~~~~~~~~~~~~~~~~~~~~~~~~~~
 
+.. rest_method::  GET /v3/{project_id}/types/{volume_type_id}/encryption/{key}
+
+To show encryption specs item for an existing volume type.
+
+Normal response codes: 200
+
+
+Request
+-------
+
+.. rest_parameters:: parameters.yaml
+
+   - project_id: project_id_path
+   - volume_type_id: volume_type_id
+   - key: key_5
+
+Response Example
+----------------
+
+.. literalinclude:: ./samples/encryption-type-specific-specs-show-response.json
+   :language: javascript
+
+
+Delete an encryption type
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
 .. rest_method::  GET /v3/{project_id}/types/{volume_type_id}/encryption/{encryption_id}
 
 Delete an encryption type.
@@ -452,7 +478,7 @@ Request
 
 
 Create an encryption type
-~~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~~~
 
 .. rest_method::  POST /v3/{project_id}/types/{volume_type_id}/encryption
 
@@ -504,7 +530,7 @@ Response Example
 
 
 Update an encryption type
-~~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~~~
 
 .. rest_method::  POST /v3/{project_id}/types/{volume_type_id}/encryption/{encryption_id}