Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Perform a second Mock tag

    tagging the sandbox project a second time to verify release automation is working as
    intended.

    Change-Id: Ib03db24d09b7fa28dd1f3893337b8670886e5686
    Signed-off-by: Aric Gardner <agardner@linuxfoundation.org>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 6d7a7ad..d20c5ac 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 6d7a7ad080d3612b80e761b439dbed91b8ae977b
+Subproject commit d20c5ac0fbec72945f72df21a61d6da4c5d45bf2