Update git submodules

* Update docs/submodules/so.git from branch 'master'
  to ab1f8407201a2fdc528916606186de83328cb752
  - Merge "Associate PNF instance with Service"
  - Associate PNF instance with Service
    
    Change-Id: I19e25e0daae042b30138bbfc074b0e651b8b1c01
    Issue-ID: SO-1274
    Signed-off-by: Lukasz Muszkieta <lukasz.muszkieta@nokia.com>
    
diff --git a/docs/submodules/so.git b/docs/submodules/so.git
index 641d9e6..ab1f840 160000
--- a/docs/submodules/so.git
+++ b/docs/submodules/so.git
@@ -1 +1 @@
-Subproject commit 641d9e6b68a964dc69dbec7c63f82e73b61433e2
+Subproject commit ab1f8407201a2fdc528916606186de83328cb752