Update git submodules

* Update docs/submodules/integration.git from branch 'master'
  to a6d37fe2d27024609815d1fafd7821c54f6b5d1d
  - update description of 5g pnf software update
    
    Signed-off-by: Yaoguang Wang <sunshine.wang@huawei.com>
    Issue-ID: INT-1104
    Change-Id: Ifcd2e0488422759ffff8789bfb0bce9ea05aab4a
    
diff --git a/docs/submodules/integration.git b/docs/submodules/integration.git
index 1d00e97..a6d37fe 160000
--- a/docs/submodules/integration.git
+++ b/docs/submodules/integration.git
@@ -1 +1 @@
-Subproject commit 1d00e970300921d28e70a8b1748f6cda67388e5c
+Subproject commit a6d37fe2d27024609815d1fafd7821c54f6b5d1d