Update git submodules

Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge changes from topic 'docs/fix-warnings'

    * changes:
      [docs] Fix unresolved reference warning
      [docs] Update broken and redirected links

  - [docs] Fix unresolved reference warning

    JIRA: YARDSTICK-1416
    Change-Id: Ibdc9b48e31aff171c59278f9ca19767392f4eeba
    Signed-off-by: Emma Foley <emma.l.foley@intel.com>
  - [docs] Update broken and redirected links

    A number of links were broken, or permenently redirected.
    Some literal include directives pointed to the wrong location.

    These have been updated, so the links are valid.

    JIRA: YARDSTICK-1416
    Change-Id: Icd20113e0ab099850fa58fa41bb27a00670f57ca
    Signed-off-by: Emma Foley <emma.l.foley@intel.com>