Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - Merge "vpn testcases added in proposed_tests"
  - vpn testcases added in proposed_tests

    JIRA: DOVETAIL-212

    after communicating with Tim/jose, help to add vpn testcase into proposed_tests

    reference: https://wiki.opnfv.org/display/sdnvpn/SDNVPN+Testing#SDNVPNTesting-TestcompliancetemplateforDovetail

    Change-Id: Id34a2cadba625abbdbc59ef11affeccba24fa10c
    Signed-off-by: MatthewLi <matthew.lijun@huawei.com>

diff --git a/docs/submodules/dovetail b/docs/submodules/dovetail
index 3bb2ec5..99a152e 160000 (submodule)
--- a/docs/submodules/dovetail
+++ b/docs/submodules/dovetail
@@ -1 +1 @@
-Subproject commit 3bb2ec53f6870b1ee9148532405573ce7624300e
+Subproject commit 99a152e76db09908d2f5984b4625ecb7f05f7ef9