Update git submodules

Update git submodules

* Update docs/submodules/apex from branch 'stable/fraser'
  - Merge "Configure NAT with baremetal when necessary" into stable/fraser
  - Configure NAT with baremetal when necessary

    We currently only enable NAT on undercloud for virtual deployments.
    However, there could be a case where a baremetal deployment also needs
    NAT as it is not using an interface on the overcloud nodes with external
    access. Therefore this patch changes the behavior to configure NAT when
    the gateway of either the external or admin (when external is disabled)
    network matches an IP assigned to the undercloud.

    JIRA: APEX-605

    Change-Id: I9c79af371913e6e5f0d39b433f68205bc7e106c5
    Signed-off-by: Tim Rozet <trozet@redhat.com>
    (cherry picked from commit d0f4951e914cacd99c750cb04a332cd7251b9de8)