Update git submodules

Update git submodules

* Update docs/submodules/releng from branch 'master'
  - jjb: xci: Add missing job blockers for XCI merge jobs

    We shouldn't allow the merge jobs to run in parallel with the verify
    ones when both are testing the same distro since one may wipe the
    'clean VM' of the other one. Moreover, we should restrict the number of
    jobs allocated on nodes in order to avoid overloading them.

    Change-Id: I9c0b9b5061e41b21c01789fc4676e72e0e082f17
    Signed-off-by: Markos Chandras <mchandras@suse.de>