Update git submodules

* Update docs/submodules/samplevnf from branch 'stable/euphrates'
  - update userguide alignment

    Change-Id: Ie938d84d31c2145167fc2b816a02bd8c0a3210ec
    Signed-off-by: Deepak S <deepak.s@linux.intel.com>

diff --git a/docs/submodules/samplevnf b/docs/submodules/samplevnf
index e38bfe2..ff7ced9 160000 (submodule)
--- a/docs/submodules/samplevnf
+++ b/docs/submodules/samplevnf
@@ -1 +1 @@
-Subproject commit e38bfe2a04a5a37a3420cf44f5702045d9ad473c
+Subproject commit ff7ced9ffeb217d692550b47e23ccc8822de7bcf