Update git submodules

* Update docs/submodules/releng from branch 'master'
  - prototypes: bifrost: Remove ironic templates

    This effectively reverts d8235c3c97f4 and 7c1b8bf89d6ce since
    upstream has now fixed the issues reported in
    https://review.openstack.org/#/c/450681/

    Change-Id: I35588146654d9141bc9357faa3d44e8799c5b706
    Signed-off-by: Markos Chandras <mchandras@suse.de>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index d0f72ad..0e4dca5 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit d0f72ad5325b200bfbbc9ae661adacd72f27afa7
+Subproject commit 0e4dca56cd9beedbbd05d033c79dc5bbd598b5cb