Update git submodules

* Update docs/submodules/usecase-ui.git from branch 'master'
  to ec06b7c5fbaba86c367b7ea6e6c4262e4e50596b
  - feat: performance-vnf page code optimization
    
    Change-Id: I679ef762638160501cdebca2925aa34f0d96bce7
    Issue-ID: USECASEUI-307
    Signed-off-by: cyuamber <xuranyjy@chinamobile.com>
    
1 file changed