Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "RFC: Set the basic structure for post merge jobs"
  - RFC: Set the basic structure for post merge jobs

    This change proposes structure for  post-merge jobs for the
    scenarios that are onboarded to XCI.

    The idea with these jobs is to verify the sanity of impacted
    scenario to find out if the version that is tested should be
    promoted to the next level in XCI; daily on baremetal.

    If it succeeds, the metadata regarding the scenario needs to
    be stored somewhere (artifact repo, etc.) so daily jobs can
    poll that location to see if there is any scenario that is
    worth testing on baremetal.

    If it fails, the scenario could be demoted instead which still
    requires further discussion and thinking. We might perhaps leave
    the metadata of the version of the scenario with previous sha
    as the candidate for testing instead of demoting it since we
    need to have working version of the scenarios at all times.

    Change-Id: I85d7176b16d0d6da45cd2462b0cdb990485b6b0d
    Signed-off-by: Fatih Degirmenci <fdegir@gmail.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 5f9c32e..640039a 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 5f9c32e9fb4048677150bf541e8f5c3cc3d43001
+Subproject commit 640039a7f889753777fe76940ff22be4f777d612