Update git submodules

* Update docs/submodules/snaps from branch 'master'
  - Set MTU=1442 in ansible_utils_tests.py

    The former MTU (1450) is fine for VXLAN but reducing it to 1442
    allows GENEVE tunneled networks.

    Else snaps_smoke fails when verifying OVN [1].

    [1] https://artifacts.opnfv.org/logs/functest/lf-pod1/gambia/2018-11-05_11-43-15/functest.log

    Change-Id: Icf38c30837858f59ed25f443245fee0007e9354d
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/snaps b/docs/submodules/snaps
index 12bdf41..7c8b405 160000 (submodule)
--- a/docs/submodules/snaps
+++ b/docs/submodules/snaps
@@ -1 +1 @@
-Subproject commit 12bdf4134e0d627b96540f514d479600f73a8545
+Subproject commit 7c8b405bc02d5b489beb359f86ba57c831648897