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>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 6357d86..9a4d570 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 6357d861c2f7c69c1486a40a81d24d7dda66eba8
+Subproject commit 9a4d570364ae9126b7886bc187cc7f7e0f9ced7f