Update git submodules

Update git submodules

* Update docs/submodules/apex from branch 'master'
  - Merge "Adding support for containerized undercloud"
  - Adding support for containerized undercloud

    Master code only supports containerized undercloud now, so this
    migration is needed.
      - Containerized services in undercloud

    We can still apply patches to THT and other non-docker services, but
    we will need to add support for patching openstack services on
    undercloud.

    Change-Id: I1ca4c6108f144efef7b5889503af265ef0fff8b2
    Signed-off-by: Ricardo Noriega <rnoriega@redhat.com>
    Signed-off-by: Tim Rozet <trozet@redhat.com>