Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - Adding a tox environment for locally building docs

    Run tox -edocs to locally build the Dovetail docs. This is quite
    useful because the default OPNFV docs preview build toolchain is
    broken for Dovetail.

    Change-Id: I0a55a701b96437a20aa09edc47bc3e49e32c0b87
    Signed-off-by: Georg Kunz <georg.kunz@ericsson.com>

diff --git a/docs/submodules/dovetail b/docs/submodules/dovetail
index 2710972..7adecf3 160000 (submodule)
--- a/docs/submodules/dovetail
+++ b/docs/submodules/dovetail
@@ -1 +1 @@
-Subproject commit 27109727907de0a275946765b201fbc0bd71116f
+Subproject commit 7adecf3d030f97ee1d19dcbda3272f88b71dd5d1