Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "bugfix: run doctor tests parallelly"
  - bugfix: run doctor tests parallelly

    Currently doctor job uses multiple 'multijob' in builders to
    virify tests in different installers, these multijobs run in sequentially
    which will cost a long time. These jobs are not related to each other in
    different installer.

    Change-Id: Idce03920ec6244a9ce288c940a24d0707af1a694
    Signed-off-by: dongwenjuan <dong.wenjuan@zte.com.cn>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index bca0fa4..859c955 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit bca0fa495ac4e1591bd062f61dbb88dad3c69a94
+Subproject commit 859c955553ac60a7fcd1af12e72031db20bbaf6a