Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - Term refstack is mentioned in dovetail Testing User Guide

    Remove refstack.log from the userguide because the refstack.log has been
    renamed dovetail.osinterop.tc00X.log

    JIRA: DOVETAIL-519

    Change-Id: Icd0bd82ef78437ab96201e58b93e0a6997f9618a
    Signed-off-by: xudan <xudan16@huawei.com>

diff --git a/docs/submodules/dovetail b/docs/submodules/dovetail
index fad3b8f..db3af2b 160000 (submodule)
--- a/docs/submodules/dovetail
+++ b/docs/submodules/dovetail
@@ -1 +1 @@
-Subproject commit fad3b8faebb29f79a6d6603ae21ccb5bf462574f
+Subproject commit db3af2b5d552d02f25660ecfa2e83595da741e9c