Update git submodules

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

    Change-Id: I00aa92a22e4e6aabd69463f3dd97d5d4a58f1e3a
    Signed-off-by: SerenaFeng <feng.xiaowei@zte.com.cn>

diff --git a/docs/submodules/qtip b/docs/submodules/qtip
index 9e84ca2..fe8d49e 160000 (submodule)
--- a/docs/submodules/qtip
+++ b/docs/submodules/qtip
@@ -1 +1 @@
-Subproject commit 9e84ca23fcd654ecb9b9bd09e14b84b6c06728f4
+Subproject commit fe8d49ebb1b563a1831341b049090388281127d3