Update git submodules

Update git submodules

* Update docs/submodules/fuel from branch 'stable/euphrates'
  - Merge "PDF parsing support" into stable/euphrates
  - PDF parsing support

    - add new git submodule pointing to OPNFV Pharos;
    - use Pharos 'generate_config.sh' to parse the PDF using the Fuel
      installer adapter and generate <pod_config.yml> dynamically;
    - build <pod_config.yml> outside current git repo and sync separately
      to prevent sensitive data leak;
    - add <pod1.yaml> PDF sample based on LF-POD2, should be used with
      'ci/deploy.sh -l local -p pod1';

    Change-Id: I4e1b95f180bcd5ade5d86f516628eb8edbe64b1c
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
    (cherry picked from commit 36e4b9754dedef27637c09b510829f686bd469e4)