Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - Update licence headers to comply with guidelines

    Updating the licence headers to comply with the community guidelines [1]
    and anteater checks.

    [1] https://wiki.opnfv.org/display/DEV/Contribution+Guidelines#ContributionGuidelines-License

    Change-Id: Idec787e32daf76c0b1bd6108977b78828125da5e
    Signed-off-by: Georg Kunz <georg.kunz@ericsson.com>

diff --git a/docs/submodules/dovetail b/docs/submodules/dovetail
index 964b0aa..b87595c 160000 (submodule)
--- a/docs/submodules/dovetail
+++ b/docs/submodules/dovetail
@@ -1 +1 @@
-Subproject commit 964b0aaceaff268d6e12d50d92ed766b8e6cd2d4
+Subproject commit b87595c644421e9ddd72ad15634382b89c902dcc