Update git submodules

* Update docs/submodules/so.git from branch 'master'
  to 78eb0176ae83484534789cafb60f773c8f8d3f44
  - Merge "Add table for OrchestrationTask in requestDB"
  - Add table for OrchestrationTask in requestDB

    Issue-ID: SO-2368

    OrchestrationTask will be used to store the
    slicing options which can be reviewed by the
    maintainer. OrchestrationTask itself is designed
    to be generic and parameters stored inside can
    be customized based on different use cases.

    Change-Id: Iec1cb31ea93659b498b30d098879a9acb711c1ee
    Signed-off-by: Harry Huang <huangxiangyu5@huawei.com>