Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "DRAFT: update release notes for Euphrates"
  - DRAFT: update release notes for Euphrates

    Change-Id: I7e437612ca52b75b71e38962a84d0dcdb453d5dd
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 14050ee..75647c2 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 14050ee3f720eb6aafaca256fc7bd982ac127cc7
+Subproject commit 75647c282ed049f033f8cb5f36b3ecc6ebd945e9