Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "functest: Build Docker images with jjb"
  - functest: Build Docker images with jjb

    docker-build: Dependency & manifest support

    Except for images that have dependencies (as functest-components,
    functest-helthcheck, functest-restapi, functest-features,
    functest-smoke, functest-vnf), all docker images
    are built SEQUENTIALLY in a multijob Phase called 'build-base-img'.
    The images with dependencies are built in PARALLEL in the second
    Phase, called 'build-child-img', only if the first Phase result is
    SUCCESFULL.
    The manifest images are created in a third Phase,
    'create-img-manifest', through opnfv-manifest.sh script, only if
    Phase 'build-child-img' result is SUCCESFULL.

    To create manifest images, a mandatory step is to preinstall
    manifest-tool on the build image dedicated VM (arm and/or amd)

    JIRA: ARMBAND-310

    Change-Id: Iaa6640568ed18a3b087db56449173841dd2757ff
    Signed-off-by: Delia Popescu <delia.popescu@enea.com>
    Signed-off-by: Fatih Degirmenci <fatih.degirmenci@ericsson.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index cbb9ada..500717b 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit cbb9adade6983dbab58a2097f7d7d89497d89093
+Subproject commit 500717bd3b46eb4855428eead7894141bf6d6a15