Update git submodules

* Update docs/submodules/fuel from branch 'stable/euphrates'
  - [docs] Add MCP user guide

    Change-Id: I97a5a2817004850abc3f702004819a907472faf7
    Signed-off-by: Cristina Pauna <cristina.pauna@enea.com>
    (cherry picked from commit e2a8202d8e95fa97026dd3031dcb6d10350132bb)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index abf9b9a..de2f8a2 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit abf9b9a8363e308daaaf297450222cf8c5397868
+Subproject commit de2f8a2d26d3a47b41e2e4a27400bb245b465ece