Update git submodules

Update git submodules

* Update docs/submodules/so.git from branch 'master'
  to 503d659ff3285bc1d07c563441c63c487f4f12e3
  - Merge "ModelInstanceName is required in SNIROHomingv2 to"
  - ModelInstanceName is required in SNIROHomingv2 to

    ModelInstanceName is required in SNIROHomingv2 to build placement
    demand. The source service does not have a modelInstanceName attribute,
    we need to set it to the service proxy modelInstanceName.

    Issue-ID: SO-2188
    Signed-off-by: Benjamin, Max (mb388a) <mb388a@att.com>
    Change-Id: I85c0940b17349c8dd5dc171954acf9f884ccff9f