Update git submodules

* Update docs/submodules/usecase-ui.git from branch 'master'
  to bfe8df3f9b7409842ddf0c9fbf41ff8b9c17c1fa
  - feat: add slicing management page in services module
    
    Change-Id: I6a9d9e7aadaff30109859df4e866da5104f26330
    Issue-ID: USECASEUI-352
    Signed-off-by: cyuamber <xuranyjy@chinamobile.com>
    
diff --git a/docs/submodules/usecase-ui.git b/docs/submodules/usecase-ui.git
index e83217f..bfe8df3 160000
--- a/docs/submodules/usecase-ui.git
+++ b/docs/submodules/usecase-ui.git
@@ -1 +1 @@
-Subproject commit e83217f0f442f6ad2c376a384b7dcd2232b254bd
+Subproject commit bfe8df3f9b7409842ddf0c9fbf41ff8b9c17c1fa