Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - update gitignore to exclude *.DS_Store *.log

    Change-Id: Ibd05768eb08336ecfa3f2454ec5548b48944126f
    Signed-off-by: rexlee8776 <limingjiang@huawei.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 96c1516..49d3585 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 96c151654bd4bd0fe469c11567f4d26b3d1e8dd2
+Subproject commit 49d358550209ab39bf618d8b226f655a0b54d13f