Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "[docs] Add info on gerrit groups to the devguide."
  - [docs] Add info on gerrit groups to the devguide.

    Added the yardstick-reviewers and yardstick-committers groups
    as an alternative to adding individual developers to a code review.

    Change-Id: I1ebba56ba27dac00f7e7af7858b3c599a0f1eae8
    Signed-off-by: Emma Foley <emma.l.foley@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 3685539..2492581 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 36855392d8f0996ec4565ac409212981ffad6a47
+Subproject commit 2492581b2d3d5fab59cd7b94b25568257f984ec4