Update git submodules

* Update docs/submodules/samplevnf from branch 'master'
  - Adding support for Ubuntu 17.10...

    Change-Id: I9a9da79cb4ccb245ccb38b50b561da51a40a359d
    Signed-off-by: Deepak S <deepak.s@linux.intel.com>

diff --git a/docs/submodules/samplevnf b/docs/submodules/samplevnf
index a9d9979..ca5ac3a 160000 (submodule)
--- a/docs/submodules/samplevnf
+++ b/docs/submodules/samplevnf
@@ -1 +1 @@
-Subproject commit a9d9979b1f5b7435552ae884da69220a42b81f81
+Subproject commit ca5ac3a8b9b3c148ce783749c0243da3ecbdfe98