Update git submodules

* Update docs/submodules/container4nfv from branch 'master'
  - build multus in ubuntu:16.04 docker during deployment

    Change-Id: I557be21c59e28401c5ec20cd43d2baabc13bef3e
    Signed-off-by: Guo Ruijing <ruijing.guo@intel.com>

diff --git a/docs/submodules/container4nfv b/docs/submodules/container4nfv
index 57c0119..ec94abf 160000 (submodule)
--- a/docs/submodules/container4nfv
+++ b/docs/submodules/container4nfv
@@ -1 +1 @@
-Subproject commit 57c01199d342c5051fef2bb94f463f21749089bb
+Subproject commit ec94abf0ea9154af2f0dbce13e12df775b72bbac