Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Bugfix: Bad substitution wthen run shell script

    When run yardstick-get-k8s-conf.sh, there is an error:
        /tmp/hudson2171423090360971912.sh: 6:
        /tmp/hudson2171423090360971912.sh: Bad substitution

    To solve this problem, we need set using /bin/bash to run script.
    If we do not set it, it will using /bin/sh by default.

    Change-Id: Ic3aa58dfad009c42974f98ea4366b6e5f50752ca
    Signed-off-by: chenjiankun <chenjiankun1@huawei.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 4e9134d..a9fe0fa 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 4e9134d73f7f52f10c637636dea2aa9b84b211a6
+Subproject commit a9fe0fa423ccac7d828574176500815a9dcd83f9