Update git submodules

* Update docs/submodules/qtip from branch 'stable/danube'
  - Merge "Add project introduction" into stable/danube
  - Add project introduction

    Change-Id: I5d0553f0ccec571f9db90b2fd8f25f0941f00b03
    Signed-off-by: Yujun Zhang <zhang.yujunz@zte.com.cn>

diff --git a/docs/submodules/qtip b/docs/submodules/qtip
index 6c185f6..19f370a 160000 (submodule)
--- a/docs/submodules/qtip
+++ b/docs/submodules/qtip
@@ -1 +1 @@
-Subproject commit 6c185f6a4541e81d1ea8124f9b8d126d60679e6f
+Subproject commit 19f370a198baabed7a6bca3a149049bbc0f9ac73