Update git submodules

* Update docs/submodules/bottlenecks from branch 'stable/danube'
  - Change PTL informatin in INFO

    Due to recent email voting results, change the PTL promotion
    result in INFO. Detailed information could be found below.
    https://lists.opnfv.org/pipermail/opnfv-tsc/2017-April/003422.html

    Change-Id: I5c942668cbe03e697bd0865cc8aee1980afed104
    Signed-off-by: yuyang <Gabriel.yuyang@huawei.com>
    (cherry picked from commit 1a3307f228055404930a7d53dc225270a70a174a)

diff --git a/docs/submodules/bottlenecks b/docs/submodules/bottlenecks
index cabe397..e6c4d13 160000 (submodule)
--- a/docs/submodules/bottlenecks
+++ b/docs/submodules/bottlenecks
@@ -1 +1 @@
-Subproject commit cabe397fbb2cb062caf74cf165b7125c38c4f697
+Subproject commit e6c4d136005fb214c676f8210337fc05f1f237ee