Update git submodules

* Update docs/submodules/usecase-ui.git from branch 'master'
  to 661ebfbca652d8f3e25da5b519ef6261d4074650
  - Merge "Automation adds release-notes.rst"
  - Automation adds release-notes.rst

    Add _release_notes hook to allow automation.
    Fix non valid release notes characters in content.

    Issue-ID: CIMAN-376
    Change-Id: I556ae597f5695399e7d8b2869542a76d8c497aa3
    Signed-off-by: lf-jobbuilder <releng+lf-jobbuilder@linuxfoundation.org>

diff --git a/docs/submodules/usecase-ui.git b/docs/submodules/usecase-ui.git
index a6854b6..661ebfb 160000 (submodule)
--- a/docs/submodules/usecase-ui.git
+++ b/docs/submodules/usecase-ui.git
@@ -1 +1 @@
-Subproject commit a6854b6aab4b4fee1f859f0694c2fe55694b16f4
+Subproject commit 661ebfbca652d8f3e25da5b519ef6261d4074650