Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Enable vnf testing when gating Functest

    It adds rally_sanity and vnfs.
    From the time being, only rally_full is excluded (all-in-one).

    Change-Id: I451d1503a0a1633f4e3e68ed272742981f04eb36
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 52c5465..69f3cc7 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 52c5465d56e30e94d8fb177ec8b3c8268de96297
+Subproject commit 69f3cc73c8c88e51864297199b945568a7dc5ce2