Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  to f8182a02158b21879e467a049991727f11c96d33
  - Update tox coverage criteria

    Two lines in dovetail_utils.py will not be covered sometimes, then the total
    coverage is 99.89%.

    Signed-off-by: xudan <xudan16@huawei.com>
    Change-Id: Iec9d0c60735b33474ec02d2ff96cad178eefd462

diff --git a/docs/submodules/dovetail b/docs/submodules/dovetail
index e705946..f8182a0 160000 (submodule)
--- a/docs/submodules/dovetail
+++ b/docs/submodules/dovetail
@@ -1 +1 @@
-Subproject commit e7059465f95bdd8222f2547af802346a04c79362
+Subproject commit f8182a02158b21879e467a049991727f11c96d33