Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "yardstick-cleanup.sh: try to fix docker rmi failure"
  - yardstick-cleanup.sh: try to fix docker rmi failure

    apex builds seem to be failing to remove the yardstick
    containers

    https://build.opnfv.org/ci/job/yardstick-apex-baremetal-daily-master/400/console

    [yardstick-apex-baremetal-daily-master] $ /bin/bash /tmp/hudson8974425724638109512.sh
    Cleaning up docker containers/images...
    Docker images to remove:
    REPOSITORY                   TAG                 IMAGE ID            CREATED             SIZE
    opnfv/yardstick              latest              5b83d8e60fb7        6 days ago          1.84GB
    Removing docker image opnfv/yardstick:latest...
    Error response from daemon: No such image: opnfv/yardstick:latest
    Build step 'Execute shell' marked build as failure

    For some reason we can't remove the yardstick container.

    Try instead to remove based on ID

    Replace grep | awk with just awk.

    Also fixed shellcheck warnings:

    In jjb/yardstick/yardstick-cleanup.sh line 6:
    if [[ -n ${dangling_images} ]]; then
             ^-- SC2128: Expanding an array without an index only gives the first element.

    In jjb/yardstick/yardstick-cleanup.sh line 10:
            containers=$(docker ps -a | grep $image_id | awk '{print $1}')
                                             ^-- SC2086: Double quote to prevent globbing and word splitting.

    In jjb/yardstick/yardstick-cleanup.sh line 12:
                docker rm -f $containers >${redirect}
                             ^-- SC2086: Double quote to prevent globbing and word splitting.

    In jjb/yardstick/yardstick-cleanup.sh line 14:
            docker rmi $image_id >${redirect}
                       ^-- SC2086: Double quote to prevent globbing and word splitting.

    In jjb/yardstick/yardstick-cleanup.sh line 20:
    if [[ ! -z $(docker ps -a | grep opnfv/yardstick) ]]; then
            ^-- SC2143: Use ! grep -q instead of comparing output with [ -z .. ].

    In jjb/yardstick/yardstick-cleanup.sh line 27:
    if [[ ! -z $(docker images | grep opnfv/yardstick) ]]; then
            ^-- SC2143: Use ! grep -q instead of comparing output with [ -z .. ].

    In jjb/yardstick/yardstick-cleanup.sh line 33:
            docker rmi opnfv/yardstick:$tag >$redirect
                                       ^-- SC2086: Double quote to prevent globbing and word splitting.

    Change-Id: I6545ac7f568161e5620e31d487faf70fa21da075
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 23829e1..d7bafeb 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 23829e1180fb8106a4a13fbbb6decf9217f291e4
+Subproject commit d7bafeb2add2600a2282b24a2c423ca696d12f42