Update git submodules

* Update docs/submodules/multicloud/k8s.git from branch 'master'
  to 4fb6acf5a720a0554c08a6f1d3526271b6317cdb
  - Merge "Correct go version installed by k8s addons"
  - Correct go version installed by k8s addons

    Andrewrothstein.go galaxy role, that was responsible for
    go installation was in too old tag to support demanded
    (1.12.4) go version. It also blocked ovn-kubernetes addon
    installation that's fixed now. Go version has been also
    upgraded to 1.12.5

    Issue-ID: MULTICLOUD-644

    Signed-off-by: Konrad Bańka <k.banka@samsung.com>
    Change-Id: I926bd061a361b2ae2efa2aecedf4fa6321f04cc8