Update git submodules

* Update docs/submodules/releng from branch 'master'
  to a52f872eec8f02db01541cb00384e0bb9b1f131e
  - Prepare backporting K8s security containers

    Change-Id: Iadd497726303be2c0491711b471d7c20f30b6447
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 115d1a7..a52f872 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 115d1a70d3f6fc1ac00595cf3f7f20bb338f4f1c
+Subproject commit a52f872eec8f02db01541cb00384e0bb9b1f131e