Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "collectd: add config file templates as package_data"
  - collectd: add config file templates as package_data

    needed for pkg_resources.resource_string

    Change-Id: Ief7a8fcd88fd6d371851a26e1559351963979e68
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index bb581e5..ab4ee80 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit bb581e5213ec07bd34a749d20adce1d9b9e6666e
+Subproject commit ab4ee807fae82dc0b426dfdc562a72ed71ca18e0