Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Propose the backporting process"
  - Propose the backporting process

    Change-Id: I0b0fddf8dfdd68fa144b28dba911352e9a4974fd
    JIRA: YARDSTICK-1253
    Signed-off-by: Emma Foley <emma.l.foley@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index a2539c8..da95727 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit a2539c884c5f21925cf0533d5c9e65c8cc3488cf
+Subproject commit da95727e2a3a9e0f816f50b40202bb231c936231