Update git submodules

* Update docs/submodules/nfvbench from branch 'stable/euphrates'
  - Updated docker tag

    Change-Id: If7b1d56d099bf8aae374baff91e8ab41572d4311
    Signed-off-by: Kerim Gokarslan <kgokarsl@cisco.com>

diff --git a/docs/submodules/nfvbench b/docs/submodules/nfvbench
index 37da1d6..695b6a5 160000 (submodule)
--- a/docs/submodules/nfvbench
+++ b/docs/submodules/nfvbench
@@ -1 +1 @@
-Subproject commit 37da1d6d2530a94d5fa2e5644bf7ae30ac9553b3
+Subproject commit 695b6a59490b7438f534f0f13606b9084922ec95