Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Add 'Signed-off-by' to automated Jenkins job patch

    All commits require a signed-off-by line to be accepted by Gerrit, and
    automated patches are no exception.

    Change-Id: I54179c47e33b5088e4e3c3d5752ccb3560f2face
    Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 92af777..c7177a0 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 92af7777ef51f8e8fe6164a27d2f69a75266dc0f
+Subproject commit c7177a0024af425493b35febd16b6bc0462836d2