Update git submodules

Update git submodules

* Update docs/submodules/fuel from branch 'stable/danube'
  - Merge "f_repobuild: Add remaining packages explicitly" into stable/danube
  - f_repobuild: Add remaining packages explicitly

    Packetary automatically solves for Fuel@OPNFV:
    - base pkgs and their deps;
    - bootstrap/target image additional pkgs;
    - explicit reqs;

    However, corner cases like "pcs", which is not in any of the
    above categories - being installed via puppet only, need to be
    added to the explicit list.

    NOTE: This enables full offline deploys for simple scenarios
    (i.e. without any plugins). Each plugin might need additional
    packages, which will be handled in further patches.
    See the bug report for more information.

    JIRA: FUEL-250

    Change-Id: Id1d31c98308cdee6cb935627984188561b560ff4
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
    (cherry picked from commit cabe0fef5a6aba50d477bdd079d922e82355c23f)