Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Set image metadata in tempest

    It applied the same operations as [1].
    Only one config is used between rally, tempest and vping.

    [1] https://gerrit.opnfv.org/gerrit/#/c/57613/

    Change-Id: I4d5fd2117d404b7eaa79326e21a35272232d0b92
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index a354230..46d61da 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit a3542307b369ab91ee24d1fed534b565cd4030d7
+Subproject commit 46d61dac3e306249e729f45d25e33c3b4d7986e9