Update git submodules

* Update docs/submodules/fuel from branch 'stable/fraser'
  - [patch] MaaS: Switch to upstream fabric/vlan mgmt

    Obsolete our out of tree patch in favor of upstream mechanisms for
    creating fabrics/VLANs/subnets.

    Change-Id: I57d6d59764a825b428f423d48c5d90af7f2e676f
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
    (cherry picked from commit 3831d538436cbf7c033b560b76f554a1dfe28a4c)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 56cfed1..af0c77a 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 56cfed1a8981a16f2671754d8aa29f7c850a0ee0
+Subproject commit af0c77ae3e7fe3b355ee0e0b08fe931d9b9af8ab