[api] Document default domain config behaviour

[Steve Martinelli]

The following are not documented in our API site:

Document default domain config: GET /domains/config/default
  http://specs.openstack.org/openstack/keystone-specs/api/v3/identity-api-v3.html#domain-configuration-management

As well as these two:
Document default for domain config group: GET /domains/config/{group}/default
Document default for domain config group option: GET /domains/config/{group}/{option}/default

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/354479

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/354479
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=5289eefd6cca723c0b2cbfe1e8a3d796f6a7ce55
Submitter: Jenkins
Branch: master

commit 5289eefd6cca723c0b2cbfe1e8a3d796f6a7ce55
Author: Tin Lam <email address hidden>
Date: Thu Aug 11 20:40:58 2016 -0500

    api-ref: Add default domain config documentation

    Add documentation for:

    GET /domains/config/default
    GET /domains/config/{group}/default
    GET /domains/config/{group}/{option}/default

    Change-Id: I1b6c8a5873edffdf4a091334b2cc0c9ce041aa62
    Closes-Bug: #1609173

[Thierry Carrez (ttx)]

This issue was fixed in the openstack/keystone 10.0.0.0b3 development milestone.