Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "bugfix: missing mcp ssh_key mapping"
  - bugfix: missing mcp ssh_key mapping

    For doctor test, we need the ssh_key to access to installer, controller
    and compute nodes in functest container.

    Change-Id: I821b7413e2e18064576c2ddbdb611eda5f3fd19b
    Signed-off-by: dongwenjuan <dong.wenjuan@zte.com.cn>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index a8e45a0..a2ffc4d 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit a8e45a0415963d8936d86df1c635f7ebec4aa5e0
+Subproject commit a2ffc4d1f172b81ec1bdf4ba7e8b00a199b97660