api-ref: Fix namespace parameter for backend capabilities

This patch set corrects the namespace parameter for capabilities
api-ref from namespace [0] to namespace_1 which is the correct
one as it is both required and matches the following format
in the view code [2]:

    The storage namespace, such as
    ``OS::Storage::Capabilities::foo``.

[0] 7f7716d584/api-ref/source/v3/parameters.yaml (L1945)
[1] 7f7716d584/api-ref/source/v3/parameters.yaml (L1951)
[2] af41c04d0f/cinder/api/views/capabilities.py (L31)

Change-Id: I0557b32e7e3752e8fcde5dadd621c82fded1e755

api-ref/source/v2/capabilities-v2.inc

@@ -37,7 +37,7 @@ Response Parameters
    - pool_name: pool_name
    - description: description
    - volume_backend_name: volume_backend_name
-   - namespace: namespace
+   - namespace: namespace_1
    - visibility: visibility
    - driver_version: driver_version
    - vendor_name: vendor_name

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

@@ -37,7 +37,7 @@ Response Parameters
    - pool_name: pool_name
    - description: description_10
    - volume_backend_name: volume_backend_name
-   - namespace: namespace
+   - namespace: namespace_1
    - visibility: visibility
    - driver_version: driver_version
    - vendor_name: vendor_name