Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 957e9ae9cb4020e68d597744dd426dfe02c31b43
  - Stop running linkcheck

    A few links are dead which asks to skip it (chicken & egg).
    It should be noted that tox should run vs patchset rather than vs
    merge.

    Change-Id: I0cd064013073b100d36c5067116e1714ebfacf97
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 546bfc3..957e9ae 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 546bfc3be1b0aa4336b889d04fea7c245b91214f
+Subproject commit 957e9ae9cb4020e68d597744dd426dfe02c31b43