Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Add wait method for Docker builds"
  - Add wait method for Docker builds

    By default, if a docker build job triggers and
    there is another one running at the same time,
    it will abort the job.
    This adds a wait method with a timeout to avoid that.

    Change-Id: Ica86885c60ce4137c85474ec4b7441ac5bab600c
    Signed-off-by: jose.lausuch <jose.lausuch@ericsson.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 8eb68cf..56cc657 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 8eb68cff96445dc53ee1c232b565aa4a61d0a526
+Subproject commit 56cc657f8cd3ed250500d90ea33da1560d90033f