Update git submodules

* Update docs/submodules/compass4nfv from branch 'master'
  - Merge "Add customized DNS server support"
  - Add customized DNS server support

    JIRA: -

    Currently Compass uses the gateway of install network as the only
    DNS server of host1 to 5. Sometimes it doesn't work in some
    environments. This patch we add a variable named USER_NAMESERVER
    which can be exported before deployment. It is used to store a
    user defined DNS nameserver.

    Change-Id: Id74889c20cf09ec7e25d882b56ab6331ee64cdcf
    Signed-off-by: Yifei Xue <xueyifei@huawei.com>

diff --git a/docs/submodules/compass4nfv b/docs/submodules/compass4nfv
index c5127c4..d2b31ca 160000 (submodule)
--- a/docs/submodules/compass4nfv
+++ b/docs/submodules/compass4nfv
@@ -1 +1 @@
-Subproject commit c5127c4efb723f080611b28307c713dd21d17d84
+Subproject commit d2b31ca70c3d8e49b7733401ce36114bd9f1c92c