Update git submodules

* Update docs/submodules/yardstick from branch 'stable/fraser'
  - Merge "[docs] Move user guide chapters to make room for new chapter." into stable/fraser
  - [docs] Move user guide chapters to make room for new chapter.

    * Increment the numbering on chapters
    * Fix some of the changes flagged by doc8

    Change-Id: I9dbf4a3d33c2b38f7567bc3493466e72a59e1a0c
    Signed-off-by: Emma Foley <emma.l.foley@intel.com>
    (cherry picked from commit 3248682fcc789f95ff8246a8d1f208a6a3abd46d)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 64c5642..408ea58 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 64c5642f0c5152ae5de728466ab3f6be4c0e24d5
+Subproject commit 408ea589283fa8181679d5d0b999bcd6785e6086