Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "run prepare-functest on opnfv vm"
  - run prepare-functest on opnfv vm

    Change-Id: Ide49917687ed583497ca089969fd2c7e7e00e548
    Signed-off-by: Periyasamy Palanisamy <periyasamy.palanisamy@ericsson.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index d7aa449..7791c88 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit d7aa449c9c9e5f74ed4908305027a7b69e858e03
+Subproject commit 7791c8816f3f268fecb39c8bce245a3dfc6c901d