Update git submodules

* Update docs/submodules/fuel from branch 'stable/euphrates'
  - Parametrized network config: nic device names

    Change-Id: I94d40529261f7753ec47a0c6a8c67ecc0fb15951
    Signed-off-by: Guillermo Herrero <guillermo.herrero@enea.com>
    (cherry picked from commit 5ab45d25c8fd3e5528c411e09b105699c745457f)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 9128c75..186e1ca 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 9128c75742f3c91d1f39741ded44ac7cec9e8809
+Subproject commit 186e1ca5b3ee1b0b76e5d6ddecfee0a94bae45fd