Update git submodules

* Update docs/submodules/stor4nfv from branch 'master'
  - userguide

    Change-Id: Id22c6199f5a6d821d652f79cf07de3d899823352
    Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com>

diff --git a/docs/submodules/stor4nfv b/docs/submodules/stor4nfv
index 6ed3685..febcef6 160000 (submodule)
--- a/docs/submodules/stor4nfv
+++ b/docs/submodules/stor4nfv
@@ -1 +1 @@
-Subproject commit 6ed368563ae3244594da858974e5c6924ece3a95
+Subproject commit febcef6118cdc8f9e5a21969c7a8d8d9637dbc14