Update git submodules

Update git submodules

* Update docs/submodules/releng from branch 'master'
  to c794dbf460eb6e27099b9b5097def4d0a1c737fd
  - Finish Airship test jobs

    It removes all debug data as all logs are now well published [1] and
    results pushed to DB [2].

    It should be noted that the two agents are configured with
    /home/jenkins/opnfv/slave_root/workspace instead of
    /home/jenkins-ci/workspace (see Functest Kubernetes slaves).

    [1] http://testresults.opnfv.org/test/api/v1/results?installer=airship&last=1
    [2] http://artifacts.opnfv.org/airship/airship-opnfv-functest-healthcheck-hunter-connection_check-run-7/results/functest.log

    Change-Id: I103bd68eb62bb5bf9c13a1f706ddf0528f874542
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>