Update git submodules

* Update docs/submodules/so.git from branch 'master'
  to df40976f9f92f24096021144f7618e8779fe5f1c
  - Merge "Add test for CreateSliceService flow"
  - Add test for CreateSliceService flow
    
    Issue-ID: SO-2368
    
    Cover preprocess
    
    Change-Id: I03466580bc688f6dc6ab0d5660eb96de395205cf
    Signed-off-by: Harry Huang <huangxiangyu5@huawei.com>
    
diff --git a/docs/submodules/so.git b/docs/submodules/so.git
index bbd4b0f..df40976 160000
--- a/docs/submodules/so.git
+++ b/docs/submodules/so.git
@@ -1 +1 @@
-Subproject commit bbd4b0f39343d3a37660a35680db433f56599179
+Subproject commit df40976f9f92f24096021144f7618e8779fe5f1c