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>
    
diff --git a/docs/submodules/usecase-ui.git b/docs/submodules/usecase-ui.git
index 17c87c1..ec06b7c 160000
--- a/docs/submodules/usecase-ui.git
+++ b/docs/submodules/usecase-ui.git
@@ -1 +1 @@
-Subproject commit 17c87c1ae1b09e22764b15af7e9a1ab04410bc5f
+Subproject commit ec06b7c5fbaba86c367b7ea6e6c4262e4e50596b