Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Clover opnfv-7.2.0 release

    Change-Id: I0cbb69f19248268765f7574087552446175c8442
    Signed-off-by: Stephen Wong <stephen.kf.wong@gmail.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 4c5f02c..cbfd380 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 4c5f02c9150533632eb8cdd5c73443fb9468feda
+Subproject commit cbfd38030595c816628b1907738a1986d8ac21f4