Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - [ha][noha] Add vpp scenario placeholder

    - dummy copy of os-nosdn-nofeature-ha masquerading as
    os-nosdn-vpp-ha scenario placeholder
    - dummy copy of os-nosdn-nofeature-noha masquerading as
    os-nosdn-vpp-noha scenario placeholder

    Change-Id: I63a302c98e6e176a480fbc110012ac66749ee88f
    Signed-off-by: Cristina Pauna <cristina.pauna@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index ffa4498..aac1f87 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit ffa4498b48cd2a07e9d3ed4ae13ce12bd2e2d231
+Subproject commit aac1f872a3cbe8d55d80a242bb0cab144ab58a4e