Update git submodules

Update git submodules

* Update docs/submodules/apex from branch 'master'
  - Fixes failure to restart containers post undercloud install

    It looks like the docker_container ansible module will recreate the
    container if it fails to restart it. This is undesired behavior so
    moving to use shell to restart the containers.

    Also, fixes mistral executor container not properly mounting the
    ceph-ansible playbook. Additionally fixes an issue with ceph-ansible by
    downgrading the package. Related rhbz:
    https://bugzilla.redhat.com/show_bug.cgi?id=1644713

    Change-Id: I3199b4af11a4170d19419f70cb53f7d74def273c
    Signed-off-by: Tim Rozet <trozet@redhat.com>