Update git submodules

Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - dovetail tool: change results dir into $DOVETAIL_HOME/results

    JIRA: DOVETAIL-381

    Now DoveTail's results dir is defined in $DOVETAIL_HOME/dovetail/conf/dovetail_config.yml,
    and its default value is /home/opnfv/dovetail/results.

    Since customer's jumphost may not have this dir and they don't want to create it,
    Dovetail needs to change this dir into $DOVETAIL_HOME/results.

    Change-Id: I616fb2da87bcfaabfd78d8762897e378168f694d
    Signed-off-by: xudan <xudan16@huawei.com>