Update git submodules

Update git submodules

* Update docs/submodules/barometer from branch 'master'
  - Merge "[userguide] Update post install verification for Apex"
  - [userguide] Update post install verification for Apex

    Since the addition of DEFAULT_ARCHIVE_POLICY to
    collectd-openstack, and support in Apex, the archive
    policy used by Gnocchi for Barometer metrics is set
    to "high" by default. This removes the need to update
    the archive policy by hand for verification.

    Change-Id: I074b4cad4926bd0e59ca04f915865ed52d0b6979
    Signed-off-by: Emma Foley <emma.l.foley@intel.com>