Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Change git base

    Change-Id: I988a95141886d53b7b14f3ab5c673f589786ae7a
    Signed-off-by: Aric Gardner <agardner@linuxfounation.org>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 7228a57..d7cbaf9 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 7228a572ab291081b3fcc5115d06c6a6901b3fea
+Subproject commit d7cbaf97e359eeed7506036cd60797a303a387ea