Update git submodules

* Update docs/submodules/fuel from branch 'stable/euphrates'
  - docs: Update installation instructions

    This documentation contains the updated procedure on how to use
    Fuel to deploy openstack.

    JIRA: FUEL-276

    Change-Id: I38dc9c57ea386a628cd363f5bcef3818739b9122
    Signed-off-by: Cristina Pauna <cristina.pauna@enea.com>
    (cherry picked from commit 1e3b2751ce0ca7fa2b011efdc76ae69dfc106ec8)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index e9f6d0c..1926f53 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit e9f6d0cfeb8dd944e2cc8ce3b1575cc33cdd6f29
+Subproject commit 1926f534bd30b195eaa8d099be2e50f164fe79cb