Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - [docs] Update mailing list to use #yardstick

    The mailing list is on a new system that lets you use #topics
    instead of [topics]. The contact information has been updated
    to reflect this.

    JIRA: YARDSTICK-1335
    Change-Id: Ida9af98f00761a3bff8903165fd2806163787ccd
    Signed-off-by: Emma Foley <emma.l.foley@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 3032d18..3fec49e 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 3032d1818a222a2fefadfb09c9e699f75da3d196
+Subproject commit 3fec49e7a3926ddf4f9303ee47a33d109421a573