Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - [MaaS] destructive storage test fio on failure

    Perform fio storage destructive test operation (usually takes just a
    few minutes) to completely destroy any previous storage metadata that
    might cause issues with cleanup in cloud-init/curtin during deploy.

    Only resort to fio when a node fails to deploy, which allows us to
    reuse the `maas.machines.mark_broken_state` state.

    JIRA: FUEL-365

    Change-Id: Ief327e6b4fefa83a8a3c131acfdf9f5fd605689d
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 2d2f599..3d6c332 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 2d2f59907d578d266e1aa19040314dc15b27c0c6
+Subproject commit 3d6c3323256d6dde62ea335e53427410f730a192