Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Enable cinder volume service

    Change-Id: I29ad8fc0e504779184fdf3795dc82ce1b031dbf8
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index de6a685..911afea 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit de6a685915bc8bd5444217bca511da35c94b4d59
+Subproject commit 911afead7d1f3ff1cf1b3c44f282e80140d45785