Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Refactor userguide "Yardstick Installation""
  - Refactor userguide "Yardstick Installation"

    [1] must be refactored in order to:
      * Include proxy options.
      * Use OpenStack client, instead of project CLI.
      * Use sudo in some commands.
      * Adapt the document to rst coding style.
      * Fix minor errors.

    JIRA: YARDSTICK-828

    [1] https://github.com/opnfv/yardstick/blob/923aa1738cbf5a8053e77e00937fc26f2142f6a3/docs/testing/user/userguide/04-installation.rst

    Change-Id: Ice63f344a8a87221bdf4daa6153b9ccac321e5b7
    Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index b237b76..7085a19 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit b237b762bbb1c9cb1a05fc46a1a67ae557791e77
+Subproject commit 7085a190cefad8c72774925dab690683d76695da