Update git submodules

* Update docs/submodules/fuel from branch 'stable/euphrates'
  - Retry cinder volume state

    The service of cinder-volume restarts too quickly after package
    installation with default/incorrect configuration and goes over restart
    threshold, so systemd stops attempt to restart any further causing
    state faulure. To fix it properly the RestartSec (i.e. restart delay)
    param should be added into cinder-volume.service unit.

    Change-Id: Ic8591e8ef52a3d439122f276d275e56bd2442ce6
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>
    (cherry picked from commit 1ea49591080442d8db86fff60031d3dc41142274)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index d047550..2d347e8 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit d047550627cd3b4d32556cfaa3608071949f773b
+Subproject commit 2d347e8fd382bbb99c9747328e41734b331f745c