Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 71b458099cd3fd8f3660543fe32aff6c039d9e68
  - Mount /home/opnfv/functest-kubernetes in testing containers

    It's needed because of docker in docker.

    Change-Id: I644710b4db88d1bf899fdd806144cdb611345a7c
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 9e56e4a..71b4580 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 9e56e4a4486d3ab9a4a53884514f44ff36fde4cb
+Subproject commit 71b458099cd3fd8f3660543fe32aff6c039d9e68