Update git submodules

Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Add network elements as a dict in Kubernetes context"
  - Add network elements as a dict in Kubernetes context

    Like in Heat context, network elements should be defined in a
    dictionary, using the network name as the entry key.

    Previous implementation:
      context:
        networks:
          - name: ...
            plugin: ...
            args: ...

    New implementation:
      context:
        networks:
          net_name_1:
            plugin: ...
            args: ...
          net_name_2: ...

    JIRA: YARDSTICK-1160

    Change-Id: I786b06555af509440604305e2c3c2c9fe521bef8
    Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>