Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "[Yardstick]Use volume-binding to provide rc file to yardstick container"
  - [Yardstick]Use volume-binding to provide rc file to yardstick container

    The 'fetch_os_creds' script is preferred to run on jump server to get OS creds as mand projects do,
    this patch unify the way to get OS creds by volume-binding.

    Change-Id: I0da54545ee088458c952f216945c29232d487692
    Signed-off-by: JingLu5 <lvjing5@huawei.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 83fef59..d51b700 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 83fef5968f000a56ecebf21ae9b089a6a39b6e33
+Subproject commit d51b7000c97e8418e81dfbafeebd4bb2ffece7fb