Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Merge "[vnode parsing] Move core logic to j2"
  - [vnode parsing] Move core logic to j2

    j2/python is easier to read and manipulate strings, although it does
    need some special care about undefined dict keys.

    With this in place, deploy.sh only contains the higher level logic for
    the deployment process.

    - merge arch-specific default configuration files into a singular
      file with arch name as main dict key of old config (also avoids
      creating duplicate 'virtual' YAML keys in $LOCAL_PDF);
    - move template handling to separate <lib_template.sh>;
    - decouple tight bash ordering of scenario expansion -> parse_yaml ->
      variable export (e.g. CLUSTER_DOMAIN) -> re-use in cluster j2s;
      however we can't parse *all* j2s in one go, as scenario j2s might
      expand to YAMLs needed while expanding cluster j2;
    - split `do_templates` into separate functions for each stage, with
      no coupling between them other then call order;

    Change-Id: I4b5e804094c00e5e918caf769fd85fa52181ad76
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 5f0ac89..6da4060 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 5f0ac8951f2630642f05dd6d06c414a9402db954
+Subproject commit 6da4060d054c66f3d0c17cfa885f6bfe171c5121