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>
    
1 file changed