Update git submodules

* Update docs/submodules/fuel from branch 'stable/euphrates'
  - [virtual] Extend cinder volume size

    Rally test of NovaServers.boot_server_attach_created_volume_and_live_migrate
    requires 10Gb volume to function, so extend volume group size in order to
    avoid insufficient free space error.

    Change-Id: I317935d2bf736db360061e24f299c9b885154a9e
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>
    (cherry picked from commit 2d95dee51177e66f5370b85115c2999925b13657)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 819ae3b..5c7924b 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 819ae3b803e358b40dd10bece841c71fcc8869ea
+Subproject commit 5c7924bda36eddd3ef8e714ac524458dacc26dcb