Update git submodules

* Update docs/submodules/samplevnf from branch 'master'
  - Adding Sample Heat template for VNFs

    This patch adds samplevnf openstack heat templates generated by
    yardstick

    Change-Id: I23295a9b66f91dc6a136a6106a46115f47da35d4
    Signed-off-by: Deepak S <deepak.s@linux.intel.com>

diff --git a/docs/submodules/samplevnf b/docs/submodules/samplevnf
index dfdeef0..12566df 160000 (submodule)
--- a/docs/submodules/samplevnf
+++ b/docs/submodules/samplevnf
@@ -1 +1 @@
-Subproject commit dfdeef016f8f2d4f14a3c01d183bff6170dcdbb9
+Subproject commit 12566dfed5cd94c21fc1ad0b1a2fab51a3e952e9