Update git submodules

* Update docs/submodules/bottlenecks from branch 'stable/danube'
  - bugfix: bottlenecks devguide in docs.opnfv.org

    JIRA: BOTTLENECK-149

    Adjust the directory structure to make Bottlenecks devguide
    on docs.opnfv.org.

    Change-Id: Ib773a26ca5f4eaee94834ff641ec45531ef3025c
    Signed-off-by: yuyang <Gabriel.yuyang@huawei.com>
    (cherry picked from commit 3480c32bb5113a8a5f56b7e1db82c3a9236418fb)

diff --git a/docs/submodules/bottlenecks b/docs/submodules/bottlenecks
index d89cd8c..1321cba 160000 (submodule)
--- a/docs/submodules/bottlenecks
+++ b/docs/submodules/bottlenecks
@@ -1 +1 @@
-Subproject commit d89cd8cf936236b4c6cb5888284e80201302f46f
+Subproject commit 1321cba0b967c89f7a23d8747a7b41d61a6424a7