Update git submodules

* Update docs/submodules/qtip from branch 'stable/danube'
  - Normalize all section headers

    - folder with `index.rst` for parts, using # with overline for heading
    - `*.rst` file for chapter, using * with overline for heading

    In each *.rst file, use the following token for heading

    - =, for sections
    - -, for subsections
    - ^, for subsubsections
    - ", for paragraphs

    Change-Id: I6c247c1f1e27e891d0dade099195ef521f7dbb72
    Signed-off-by: Yujun Zhang <zhang.yujunz@zte.com.cn>

diff --git a/docs/submodules/qtip b/docs/submodules/qtip
index 88f69a8..0c8fdfa 160000 (submodule)
--- a/docs/submodules/qtip
+++ b/docs/submodules/qtip
@@ -1 +1 @@
-Subproject commit 88f69a8d9977228a225333f084dc95adc2312f13
+Subproject commit 0c8fdfafa8a85dd6e25497a9f9af9694e75ee4a1