Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Create Gambia Jobs for Yardstick 1/2

    Add Gambia jobs for Yardstick gate:
    - yardstick-verify-gambia
    - yardstick-merge-gambia
    Keep fraser jobs until Gambia 7.0.0 is released.

    Gambia jobs for Yardstick daily will be added in next patch.

    Change-Id: Id02bcb8197dd1f6d0b8f5baddef684a97e269a14
    Signed-off-by: jenkins-ci <jenkins-opnfv-ci@opnfv.org>
    Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>
    Signed-off-by: rexlee8776 <limingjiang@huawei.com>
    Signed-off-by: Patrice Buriez <patrice.buriez@intel.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 6c91cbf..c963866 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 6c91cbf3eb811e9993cc6e875dcd4b91357545ac
+Subproject commit c9638663f74ad36eb775c9b6eaabf4d240277929