Update git submodules

* Update docs/submodules/container4nfv from branch 'stable/euphrates'
  - Add K8s Installation Guide

    Change-Id: I293a48d25b1a7674f0105ced4b4d30facbd50aec
    Signed-off-by: Guo Ruijing <ruijing.guo@intel.com>

diff --git a/docs/submodules/container4nfv b/docs/submodules/container4nfv
index 644f51f..3045a42 160000 (submodule)
--- a/docs/submodules/container4nfv
+++ b/docs/submodules/container4nfv
@@ -1 +1 @@
-Subproject commit 644f51f420a38b494a2c6af60ac5a8134c733931
+Subproject commit 3045a42ee7cf729346c0638a21411a239e9474b6