Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - bugfix: hosts info is wrongly processed

    changes:
    1. add usage example in hosts.yaml.sample
    2. fix /etc/hosts from wrong format {'hostname': 'ip'} to
       the right 'ip hostnames'
    3. fix --add-hosts from wrong usage --add-host {'hostname': 'ip'} to
       the right --add-host='hostnames':ip
    4. support per ip mapping mutiple hostnames, which is also
       in line with /etc/hosts schema

    JIRA: DOVETAIL-556

    Change-Id: I92e8cb0fd3476b61f5c73a69e34c4a66aef51d6e
    Signed-off-by: SerenaFeng <feng.xiaowei@zte.com.cn>

diff --git a/docs/submodules/dovetail b/docs/submodules/dovetail
index 81ea24a..2b09051 160000 (submodule)
--- a/docs/submodules/dovetail
+++ b/docs/submodules/dovetail
@@ -1 +1 @@
-Subproject commit 81ea24a3e8fca5a11191129e92ab1b9bc985759d
+Subproject commit 2b090511832f1898f7d15cc33a6b9b20a8d88e07