Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "use py34 for tox"
  - use py34 for tox

    Change-Id: I606e0de73e153de88d592a36d4eaabf1b4690e6c
    Signed-off-by: dongwenjuan <dong.wenjuan@zte.com.cn>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 1602063..09cfb60 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 1602063f65e7a2b8615280e7682857322f28bcd5
+Subproject commit 09cfb60453d9cfa317c5e5d317c48823d23c6258