Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Merge "[docs] add info about block storage support"
  - [docs] add info about block storage support

    Adding volumes in openstack by default uses virtio_blk which limits
    the amount of disks that can be attached. Here we inform about
    this shortcoming and supply a workaround.

    JIRA: ARMBAND-376

    Change-Id: I711df5c19befca7a3abfdce9fe9b2b0bb38853ac
    Signed-off-by: Charalampos Kominos <Charalampos.Kominos@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 5652931..385b39e 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 5652931324e9ae9495b9d731f53a482487b2f74f
+Subproject commit 385b39e529434d39ac19985a5f5624f1cdbef425