Update git submodules

* Update docs/submodules/nfvbench from branch 'stable/euphrates'
  - NFVBENCH-41 Add fluentd result tag to nfvbench server

    Change-Id: I8fc274d9f9ee2211636336bc58f43f4d105986ef
    Signed-off-by: Kerim Gokarslan <kgokarsl@cisco.com>

diff --git a/docs/submodules/nfvbench b/docs/submodules/nfvbench
index c528972..d5c0e0a 160000 (submodule)
--- a/docs/submodules/nfvbench
+++ b/docs/submodules/nfvbench
@@ -1 +1 @@
-Subproject commit c528972bfe3dbc4100e9b2b486785d2b03599cf8
+Subproject commit d5c0e0adeeaf80f4c6eefb24e70e94eca636173b