Update git submodules

* Update docs/submodules/yardstick from branch 'stable/euphrates'
  - Docs: add yardstick gui descrption in userguide

    Change-Id: I09bc55e296d2c641f10819972ec0d48a289432b8
    Signed-off-by: JingLu5 <lvjing5@huawei.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 479a571..1f04604 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 479a571e913f29178990458ad02fb62cd6cb843e
+Subproject commit 1f04604b780674d6aede2bac75a643bb1d993576