Update git submodules

* Update docs/submodules/fuel from branch 'stable/euphrates'
  - Merge "docs: Update release documentation" into stable/euphrates
  - docs: Update release documentation

    JIRA: FUEL-276

    Change-Id: I09799b2dde3c992d229864757e655c108d33608a
    Signed-off-by: Cristina Pauna <cristina.pauna@enea.com>
    (cherry picked from commit 029462bc462b1dea05920464b8d0acc77f789eef)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 1926f53..ff43473 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 1926f534bd30b195eaa8d099be2e50f164fe79cb
+Subproject commit ff434739425a9c30186c54318ae05431a9493196