Update git submodules

Update git submodules

* Update docs/submodules/multicloud/k8s.git from branch 'master'
  to d18501a4c4b15ee99e600ec6a5385616021812b4
  - Merge "Add static compile time check to plugins"
  - Add static compile time check to plugins

    Add a static compile time check to
    plugins to make sure that any interface implementation
    mismatch is caught at compile time rather than runtime.

    Issue-ID: MULTICLOUD-666
    Change-Id: I7f57774ad9384edb874cf64534f521014aea422f
    Signed-off-by: Kiran Kamineni <kiran.k.kamineni@intel.com>