Update git submodules

* Update docs/submodules/fuel from branch 'stable/euphrates'
  - Merge "[baremetal] PDF: Use net_admin for MaaS PXE net" into stable/euphrates
  - [baremetal] PDF: Use net_admin for MaaS PXE net

    While at it, fix another small issue where a variable
    (parameters__param_opnfv_maas_pxe_address) was used without being
    populated (defined in 'runtime.yml', which is not read using
    `parse_yaml`, like the scenario yml or the PDF expanded class,
    pod_config.yml).

    JIRA: FUEL-313

    Change-Id: Iee88601d5420f55572bf90c8cf330afbedfb2e21
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
    (cherry picked from commit 9136aef95f77a1f26175929caedfe6ae662bbbd8)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 8007028..08bde71 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 8007028f48b57243c428cdc9ebbbc168c2e373cc
+Subproject commit 08bde71385047eefcd7ac6aa211df5a83c145bdb