Update git submodules

* Update docs/submodules/qtip from branch 'master'
  - Merge "Include index files in master doc"
  - Include index files in master doc

    some files were missing because we manually maintain the root index and it
    is out of sync with the child index

    Change-Id: If26474952931bfbfb9c7c2acf8331cbd54a1ccec
    Signed-off-by: Yujun Zhang <zhang.yujunz@zte.com.cn>

diff --git a/docs/submodules/qtip b/docs/submodules/qtip
index d15914f..4594ef7 160000 (submodule)
--- a/docs/submodules/qtip
+++ b/docs/submodules/qtip
@@ -1 +1 @@
-Subproject commit d15914ff7f4be5ad7bd3812f9214d73d123996a5
+Subproject commit 4594ef75c5fa7fcf8013f6558a2940884a922e20