Update git submodules

* Update docs/submodules/releng from branch 'master'
  - prototypes: bifrost: Add keystone roles

    The os_client_config Ansible module used by all the ironic-* roles
    depends on the keystone roles so we need to make use of them even
    though they do not affect the end result. This fixes the following
    OPNFV CI problem due to not having a clouds.yaml file present to
    be consumed by the os_client_config Ansible module.

    fatal: [controller00]: FAILED! => {"censored": "the output has been hidden due to the fact that 'no_log: true' was specified for this result"}
    An exception occurred during task execution. The full traceback is:
    Traceback (most recent call last):
      File "/tmp/ansible_ApkCUQ/ansible_module_os_client_config.py", line 75, in <module>
        main()
      File "/tmp/ansible_ApkCUQ/ansible_module_os_client_config.py", line 63, in main
        for cloud in config.get_all_clouds():
      File "/usr/lib/python2.7/site-packages/os_client_config/config.py", line 798, in get_all_clouds
        cloud, region_name=region['name']))
      File "/usr/lib/python2.7/site-packages/os_client_config/config.py", line 1071, in get_one_cloud
        auth_plugin = loader.load_from_options(**config['auth'])
      File "/usr/lib/python2.7/site-packages/keystoneauth1/loading/base.py", line 162, in load_from_options
        raise exceptions.MissingRequiredOptions(missing_required)
    keystoneauth1.exceptions.auth_plugins.MissingRequiredOptions: Auth plugin requires parameters which were not given: auth_url
    fatal: [opnfv]: FAILED! => {"censored": "the output has been hidden due to the fact that 'no_log: true' was specified for this result"}

    Moreover, we cleanup the ~/openstack directory which may contain some
    bifrost artifacts such as a clouds.yaml file.

    Finally, we use 'sudo -H' because for the keystone roles we need the HOME
    variable to be set properly.

    Change-Id: I45b08bd33dd8ea9505fe10eb4b2b10956b3b683c

diff --git a/docs/submodules/releng b/docs/submodules/releng
index fc5f95a..6769ae9 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit fc5f95a30145e201ea6bc484d14598a6783ec4da
+Subproject commit 6769ae9bcbf61dc079c42ee5ebfafcaaf9fd708a