Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "create stable/fraser branch for container4nfv"
  - create stable/fraser branch for container4nfv

    Change-Id: Id003f2c01eb979c9745079d34f1556ae69ac984e
    Signed-off-by: Guo Ruijing <ruijing.guo@intel.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index e401525..f331748 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit e4015259ed48cad441fe7607403fbcd1c21b86e3
+Subproject commit f331748f96b8ea8d78be5bc5718f1559f6bed4d3