Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Remove old GS-Cleanup Job from Apex"
  - Remove old GS-Cleanup Job from Apex

    This job template isn't attached to a job, so it doesn't even get
    executed; Further, artifact cleanup is take care of by
    'releng-artifact-cleanup-daily-{stream}'

    Change-Id: I3e4d0339650f0507b8a3cd1512c2ca643f4fe75a
    Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index d040efc..3d39c8e 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit d040efc3be330026148c83e434a5d2b80c1543dc
+Subproject commit 3d39c8ea99b850b728f2b7753e139943bdcc0807