Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - Remove 2 sub test cases from neutron_trunk check list

    1. neutron.tests.tempest.api.test_trunk.TrunkTestJSON.test_create_update_trunk
    This test case will get the value of key 'revision_number' [1],
    While this is a new extension for Newton and not support by Mitaka.
    Please refer to the history of neutron github and the differences between
    mitaka tag [3] (which has no file revisions.py) and newton [4].

    2. neutron.tests.tempest.api.test_trunk.TrunkTestJSON.test_show_trunk_has_project_id
    This test case requires extension 'project-id' [5], while this is also a new
    extension for Newton. Please refer to the history of neutron [6] and the difference
    between mitaka tag [3] (which has no file project_id.py) and newton [7].

    Also it is a little unreasonable to check both tenant_id and project_id.
    For some products, they may only have either tenant_id or project_id (not both).
    Has sent an email to the neutron_trunk team but get no feedback until now.

    [1] https://github.com/openstack/neutron/blob/stable%2Fpike/neutron/tests/tempest/api/test_trunk.py#L123
    [2] https://github.com/openstack/neutron/commits/newton-eol/neutron/extensions/revisions.py
    [3] https://github.com/openstack/neutron/tree/mitaka-eol/neutron/extensions
    [4] https://github.com/openstack/neutron/blob/newton-eol/neutron/extensions/revisions.py
    [5] https://github.com/openstack/neutron/blob/stable%2Fpike/neutron/tests/tempest/api/test_trunk.py#L110
    [6] https://github.com/openstack/neutron/commits/newton-eol/neutron/extensions/project_id.py
    [7] https://github.com/openstack/neutron/blob/master/neutron/extensions/project_id.py

    JIRA: DOVETAIL-723

    Change-Id: Idb4a56d47148b14ae4674549f98b1be65e9b8f15
    Signed-off-by: xudan <xudan16@huawei.com>

diff --git a/docs/submodules/dovetail b/docs/submodules/dovetail
index d1f154c..84c6a77 160000 (submodule)
--- a/docs/submodules/dovetail
+++ b/docs/submodules/dovetail
@@ -1 +1 @@
-Subproject commit d1f154cbd3816319a7abd491b7128480626c2ceb
+Subproject commit 84c6a770b9ef694cc86bea1e3930c56787552aa1