Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 4fe72d3acc00d372b2ab19239f24ddd2996366cf
  - Build latest Functest Kubernetes images

    Change-Id: I8ad1c0c8ef937870dba5d2ce8f9817217278c37f
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index e4e7eee..4fe72d3 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit e4e7eeec66f7f34117a13c23a908bf6dec97f95e
+Subproject commit 4fe72d3acc00d372b2ab19239f24ddd2996366cf