Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - Bugfix: There is an exception when crawling Yardstick results

    If there is no pod.yaml, the results data looks like,
    {"status": 2, "result": "[Errno 2] No such file or directory: u'/home/opnfv/userconfig/pre_config/pod.yaml'"}

    It will get an exception when reading value from file,
    File "/usr/local/lib/python2.7/dist-packages/dovetail/report.py", line 327, in crawl_from_file
    criteria = data['result']['criteria']
    TypeError: string indices must be integers

    https://build.opnfv.org/ci/view/dovetail/job/dovetail-apex-baremetal-default-mandatory-master/52/console

    Change-Id: I73ca3e5ae73433a2dc139789df4d67e8c583be08
    Signed-off-by: xudan <xudan16@huawei.com>

diff --git a/docs/submodules/dovetail b/docs/submodules/dovetail
index dcd1697..7694795 160000 (submodule)
--- a/docs/submodules/dovetail
+++ b/docs/submodules/dovetail
@@ -1 +1 @@
-Subproject commit dcd16973180f55be907c79f074040b498c3088b9
+Subproject commit 76947950b0196367768068ae31f85ca175b672fb