Update git submodules

* Update docs/submodules/sdc.git from branch 'master'
  to c6f9f152bbed844843e4f2a137bcfa1b726dd81f
  - Ability to update PNF with new version of VSP
    
    Change-Id: Ie08d905bd40761b23198ad806be1750291343aae
    Issue-ID: SDC-2219
    Signed-off-by: kooper <sergey.sachkov@est.tech>
    
diff --git a/docs/submodules/sdc.git b/docs/submodules/sdc.git
index b2f9dc5..c6f9f15 160000
--- a/docs/submodules/sdc.git
+++ b/docs/submodules/sdc.git
@@ -1 +1 @@
-Subproject commit b2f9dc5d3bc02564b4d952caa0bf2ccd20dfc6af
+Subproject commit c6f9f152bbed844843e4f2a137bcfa1b726dd81f