Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Replace nova attach volume to server with shade client."
  - Replace nova attach volume to server with shade client.

    Function attach_volume_to_server now uses shade client
    instead of nova client.

    JIRA: YARDSTICK-1088

    Change-Id: Id00df672c2c195b5c338cbbc30ddf2742a4e4d29
    Signed-off-by: Shobhi Jain <shobhi.jain@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index fe0edc2..b05c134 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit fe0edc2eaf5ff60089f55d1860fdc20b343170c9
+Subproject commit b05c13458ce6afef1171cd8463b7053e489d0497