Update git submodules

Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "xci: Create periodic bifrost jobs to find working version"
  - xci: Create periodic bifrost jobs to find working version

    These jobs run periodically against the HEAD of master and stable/ocata
    branches in order to attempt provisioning and help us to find more
    recent working versions to pin.

    In perfect world, these jobs should be run post-merge, helping us
    to move faster but lack of resources prevent us doing that.

    Change-Id: I6f6b2fcc58eda112b1e811a7b11269e928bbceef
    Signed-off-by: Fatih Degirmenci <fatih.degirmenci@ericsson.com>