Update git submodules

* Update docs/submodules/dovetail from branch 'stable/fraser'
  - Updating test case requirements

    Updating the test case requirements document to match the new test case
    naming convention which was introduced for the 2018.08 release.
    Additionally, minor syntactic fixes.

    Change-Id: I34b4b90eb4f8bab4f59df2415c98c27169e98332
    Signed-off-by: Georg Kunz <georg.kunz@ericsson.com>
    (cherry picked from commit fe8866c96dd7081a1a2b5a231574c36dde660f3f)

diff --git a/docs/submodules/dovetail b/docs/submodules/dovetail
index 16d006c..23ecd96 160000 (submodule)
--- a/docs/submodules/dovetail
+++ b/docs/submodules/dovetail
@@ -1 +1 @@
-Subproject commit 16d006c464828f2545014bd7b1da2141af0b62b9
+Subproject commit 23ecd96cdec73d4d32daf4fe6e72944956e923ed