Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "heat: use dict literal in init_template"
  - heat: use dict literal in init_template

    prefer dict literals when possible over increment assignment.

    Change-Id: Ia40bbc04eed61feb036a1e9ec3b3110b03c095e1
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 5c8e386..8b8738e 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 5c8e38667e17059db1c62dd21f868966a6b2a519
+Subproject commit 8b8738ed675f8aab93d484df300e3d0c6c24becc