Update git submodules

Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Merge changes from topic 'add-role-hooks'

    * changes:
      xci: playbooks: Add generic playbook for scenarios to plug their roles
      xci: Clone all XCI scenarios in advance similar to a-r-r
      xci: xci-deploy.sh: Allow scenarios to overrides XCI variables.

  - xci: playbooks: Add generic playbook for scenarios to plug their roles

    The new bootstrap-scenarios.yml playbook is aimed to be used by
    scenarios to configure themselves right before we proceed with
    the bootstrapping. This way we can avoid having scenario specific
    stuff into the generic code.

    Change-Id: I3026013719a50458c65405439712270f25f569ff
    Signed-off-by: Markos Chandras <mchandras@suse.de>
  - xci: Clone all XCI scenarios in advance similar to a-r-r

    In order to plug the scenarios' roles properly, we need to have all
    roles physically present in advance. As such, add a
    opnfv-scenario-requirements.yml file which can be used to populate the
    roles directory with all the scenarios.

    Change-Id: I0cdadb63849e4565c31559817660d23217879053
    Signed-off-by: Markos Chandras <mchandras@suse.de>
  - xci: xci-deploy.sh: Allow scenarios to overrides XCI variables.

    Scenario may want to override variables exported by the XCI so
    allow them to define their own 'xci_overrides' file in the root directory
    of the role to do so.

    Change-Id: I6648eb43831a2aecc08d745a8c0fc191ce56e1b2
    Signed-off-by: Markos Chandras <mchandras@suse.de>