Update git submodules

* Update docs/submodules/yardstick from branch 'stable/fraser'
  - Merge "Update docker image tag to 6.2.0" into stable/fraser
  - Update docker image tag to 6.2.0

    Change-Id: Iec55c8f400d5413f173359d21cb1cc3b3d4f935f
    Signed-off-by: Emma Foley <emma.l.foley@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 98aca83..a46467e 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 98aca839a400b0933d474c1358aa601f36b67369
+Subproject commit a46467e5d769c888db3b982fe74e9708a67884d5