Update git submodules

Update git submodules

* Update docs/submodules/releng from branch 'master'
  - jjb: xci: bifrost-verify: Simplify bifrost job

    We no longer test OPNFV commits that affect bifrost since these are
    being tested as part of the XCI jobs. As such, simplify the job to
    only test incoming upstream patchsets. Moreover, we need to block
    when an XCI job is running since both jobs run on the same hosts and
    create the same VMs.

    Change-Id: I5c11ae5b6a4d719ec41a6e663ddf6ecbd71ac1a5
    Signed-off-by: Markos Chandras <mchandras@suse.de>