Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - Merge "Tag dovetail with cvp.0.4.0"
  - Tag dovetail with cvp.0.4.0

    JIRA: DOVETAIL-476

    1. docker image used
       yardstick: danube.3.1
       functest: cvp.0.2.0
       bottlenecks: cvp.0.4.0
       testapi: cvp.0.4.0
       dovetail: cvp.0.4.0
    2. main changes
       Add docs about vping test cases (test scope and test specification)
       Add 2 vping test cases into proposed_tests
       Bugfix: Build docker image failed because of lacking of packages
       Add resiliency.tc001 into proposed_tests
    3. For more information, refer to
       https://wiki.opnfv.org/display/dovetail/Running+history+for+the+dovetail+tool

    Change-Id: I5ce6bdc9a1daa957124309c9fadc532f9c7a2b1e
    Signed-off-by: xudan <xudan16@huawei.com>

diff --git a/docs/submodules/dovetail b/docs/submodules/dovetail
index fc37fef..a8d7665 160000 (submodule)
--- a/docs/submodules/dovetail
+++ b/docs/submodules/dovetail
@@ -1 +1 @@
-Subproject commit fc37fef338a99254c64cc5c8cb5e1e29ec7ecdb1
+Subproject commit a8d7665ca783684bc10d7c3dbbc606e30f083bc7