Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - hosts info config in container

    JIRA: DOVETAIL-435

    in some SUT, there's a need to config hosts <domain name>:<ip> info
    in container /etc/hosts, ortherwise, SUT service will not be used.

    usage:

    1,for dovetail directly running, cd ${DOVETAIL_HOME}/userconfig
      vim hosts.yaml
      sth like
      hosts_info:
        - domain_nameA:192.168.33.101
        - domain_nameB:<some IP>
    2,for dovetail container running, first get inside the container,
      cd /home/opnfv/dovetail/userconfig
      vim hosts.yaml
      same as 1.

    Change-Id: Ic5d87df3d78c0fa1d08c4e972c0fc97e61b906e9
    Signed-off-by: MatthewLi <matthew.lijun@huawei.com>

diff --git a/docs/submodules/dovetail b/docs/submodules/dovetail
index 90cbc07..84e7b3b 160000 (submodule)
--- a/docs/submodules/dovetail
+++ b/docs/submodules/dovetail
@@ -1 +1 @@
-Subproject commit 90cbc0764d68369a0a6ce0fe09112e73fef2e760
+Subproject commit 84e7b3b030018fd3f464bfa9c47c1df9d07ce675