Update git submodules

Update git submodules

* Update docs/submodules/oom.git from branch 'master'
  to 6516cd5988ce5ef6d63de8b3e3d9890f02bd5791
  - Merge "fixing not working repository:image"
  - fixing not working repository:image

    image can't be pulled from registry.hub.docker.com repository hence
    changing it to working one.

    non-working ==> registry.hub.docker.com/onap/multicloud/framework-artifactbroker:1.4.2
    working ==> nexus3.onap.org:10001/onap/multicloud/framework-artifactbroker:1.4.2

    Issue-ID: MULTICLOUD-844

    Signed-off-by: Ondřej Šmalec <o.smalec@partner.samsung.com>
    Change-Id: I1449cc0ff4a2fb4a5f4230515e9422f32cdbf5b5