Update git submodules

* Update docs/submodules/yardstick from branch 'stable/danube'
  - Merge "Bugfix: fix ubuntu image name typo" into stable/danube
  - Bugfix: fix ubuntu image name typo

    Change-Id: I8722f2ddd096bc784f45d4bcf58ea6a84d319fb2
    Signed-off-by: JingLu5 <lvjing5@huawei.com>
    (cherry picked from commit 571ee6afca03120c393def421eb35a466f9a940b)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 132564d..7f445a3 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 132564dc6b19cea9145b23332a04c258d1182f64
+Subproject commit 7f445a38e9bc572cce0c7616a24480e7c7b31109