Update git submodules

Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - [HA] Use cluster_public_host for SSL cert fetch

    For VCP-enabled scenarios, `cluster_public_host` and
    `cluster_vip_address` both point to the public VIP of the cluster.
    However, for upcoming NOVCP scenarios, `cluster_vip_address` resides
    inside the management segment, so use `cluster_public_host` instead.

    JIRA: FUEL-310

    Change-Id: I13ef482e2c3116c991dfe91be81d0964f140f8e9
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>