Update git submodules

* Update docs/submodules/fuel from branch 'stable/euphrates'
  - Add license headers where missing

    While at it, compact 'set' into bash shebang where possible and
    add `make patches-copyright` target to simplify adding patch
    license headers.

    Change-Id: I0c841de72e5709e5eef915a52c5ec4a7fc0f7c37
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
    (cherry picked from commit 644e5fdfa2f49b988a5150e2a4eefc12daecd845)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index ef570e8..94825e2 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit ef570e8954b44fd608cf1ff5e50b5cbc3d0d178f
+Subproject commit 94825e25dcc5bf4a8490690fc1cf423df0e9d7fe