Update git submodules

* Update docs/submodules/fuel from branch 'stable/euphrates'
  - Merge "docs: Update prx nodes on network diagrams" into stable/euphrates
  - docs: Update prx nodes on network diagrams

    - prx: added 3rd interface, green dot to mgmt

    JIRA: FUEL-302

    Change-Id: I9f807409ed7a84de95d7321f059343d5d676038e
    Signed-off-by: Guillermo Herrero <guillermo.herrero@enea.com>
    (cherry picked from commit e62317704bce4985dc12abeb2de729a56397426b)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index e9bbe18..db70312 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit e9bbe18583701a3e54ef229b36b8ad729008ae66
+Subproject commit db70312b2d2b99fdc61558477166aab7263c0488