Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "xci: Enable voting for CentOS jobs"
  - xci: Enable voting for CentOS jobs

    CentOS is now supported by os-nosdn-nofeature scenario and it is
    time to enable voting for it. For scenarios that do not support
    CentOS yet, the jobs will skip running real stuff by exit 0 in
    order not to fail the patch.

    Change-Id: I86c9e1bb4d66ea84ccfc864186a7ca7c696f8663
    Signed-off-by: Fatih Degirmenci <fdegir@gmail.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 4253e65..280ae93 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 4253e653aa572973577015286232635c4a81ceb1
+Subproject commit 280ae93b3d91bbd84db9b7aa20f7f5513b8afd7e