Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Sync requirements with OpenStack Pike"
  - Sync requirements with OpenStack Pike

    OPNFV F-release is built on top of OpenStack Pike.
    Functest depends on releng/modules and requires this update.

    It conforms with the requirement management cleant for E-release [1].

    [1] https://wiki.opnfv.org/display/functest/Requirements+management

    Change-Id: If3c3a607c8d2d5515ada78b03104067937fb4b37
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 15ce869..1ab9e70 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 15ce86943f97857173114fca89246b1cbba1925e
+Subproject commit 1ab9e70f4acbea14df8b2936636477873ab70480