Update git submodules

* Update docs/submodules/qtip from branch 'stable/danube'
  - Merge "cite danube.rst in index.rst" into stable/danube
  - cite danube.rst in index.rst

    Change-Id: I00aa92a22e4e6aabd69463f3dd97d5d4a58f1e3a
    Signed-off-by: SerenaFeng <feng.xiaowei@zte.com.cn>
    (cherry picked from commit 7bae1022dcb5fd89016254b70566721e8b59eae3)

diff --git a/docs/submodules/qtip b/docs/submodules/qtip
index e35bf4e..adb0769 160000 (submodule)
--- a/docs/submodules/qtip
+++ b/docs/submodules/qtip
@@ -1 +1 @@
-Subproject commit e35bf4e340cbc3b971327ad51445c766c7c3803e
+Subproject commit adb0769729fd2558fb41edfc6d3fc84f2b2a9030