Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Add documentation for scenarios

    Added documents for feature scenarios supported by fuel.
    The nofeature scenarions don't require documentation.

    Change-Id: I574e42b60125b4a59c8d921fa45e4c4fbf09137f
    Signed-off-by: Cristina Pauna <cristina.pauna@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 92530f8..2a74900 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 92530f89c061b0070766e431f839feb368e2e4ac
+Subproject commit 2a74900ecd451c939a34d53a529e802cc2250db9