Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - Merge "Fix the docker version to be 17.03.0-ce rather than the latest one"
  - Fix the docker version to be 17.03.0-ce rather than the latest one

    JIRA: DOVETAIL-467

    1. Since the script getting with "wget qO https://get.docker.com/" has been
       changed and it can just install docker-ce rather than docker-engine now.
    2. Dovetail validates with Docker 17.03 CE, so the docker installed in the
       dovetail container can be 17.03.0-ce.

    Change-Id: If64204ba3dcf5a38d7a124a0cc716f8375808999
    Signed-off-by: xudan <xudan16@huawei.com>

diff --git a/docs/submodules/dovetail b/docs/submodules/dovetail
index 017fb8d..7c786e5 160000 (submodule)
--- a/docs/submodules/dovetail
+++ b/docs/submodules/dovetail
@@ -1 +1 @@
-Subproject commit 017fb8d0d9fc1eed7cbaa7605b3fe8074ef187df
+Subproject commit 7c786e5f7815dc7d1ba8259e0a9d4acc0981bfd4