Update git submodules

Update git submodules

* Update docs/submodules/so.git from branch 'master'
  to 42b399ea943940ef1e37c267a9aea03b5f01f2d0
  - Merge "Add SO Update Check if SDC activities deployment end point for custom worlflows is alive"
  - Add SO Update Check if SDC activities deployment end point for custom worlflows is alive

    Make changes to verify if SDC activities deployment
    end point(mso.asdc.config.activity.endpoint)  for custom worlflows is alive
    Issue-ID: SO-2294
    Signed-off-by: Bonkur, Venkat (vb8416) <vb8416@att.com>
    Change-Id: Iff916a33b403d507a383cebf8d668bb5cbf9fb55