Update git submodules

* Update docs/submodules/samplevnf from branch 'master'
  - Merge "Fix potential crash when issuing "tx distr stop" command."
  - Fix potential crash when issuing "tx distr stop" command.

    Change-Id: I9ef89020d203674f6c3301653ab2ff9d623665b6
    Signed-off-by: Xavier Simonart <xavier.simonart@intel.com>

diff --git a/docs/submodules/samplevnf b/docs/submodules/samplevnf
index dd77bd8..95a6421 160000 (submodule)
--- a/docs/submodules/samplevnf
+++ b/docs/submodules/samplevnf
@@ -1 +1 @@
-Subproject commit dd77bd89e11d84d378167468db85fb4ef35a0c7a
+Subproject commit 95a6421555054f0fd3f78a5e2e21f461eee84886