Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "pass user_data to heat template"
  - pass user_data to heat template

    We had code to support adding user_data but the
    Server model was not connected.

    The string formatting of the user_data is left
    as an exercise for the reader.

    Change-Id: I298657b93de67e19436bca616b119df636dacce2
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 67da8f2..e692c1c 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 67da8f2ddb5cbf14bbf0df48b10240ba6ebadbe9
+Subproject commit e692c1c8fab6447bc1acfcec612a0867a4c877b5