Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Add dependencies to Ubuntu Builders"
  - Add dependencies to Ubuntu Builders

    Installs dependencies needed by barometer, dovetail, yardstick and
    functest.

    Change-Id: Ie9a20c45ef9b3251f2b861da7151114094044394
    Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index cdb60a4..726b96c 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit cdb60a4b93c166f8610caac60d128449faeacd35
+Subproject commit 726b96c6746aba86c253a5505561a4d96426115f