Update git submodules

* Update docs/submodules/bottlenecks from branch 'master'
  - bugfix: copy hosts file

    JIRA: BOTTLENECK-227

    Operation of copying hosts file should follow the building of
    Yardstick docker

    Change-Id: I4d66efe8b823876a733d1877c26d1e0e263ca4da
    Signed-off-by: Yang Yu <Gabriel.yuyang@huawei.com>

diff --git a/docs/submodules/bottlenecks b/docs/submodules/bottlenecks
index 28ac6b8..7b61cfd 160000 (submodule)
--- a/docs/submodules/bottlenecks
+++ b/docs/submodules/bottlenecks
@@ -1 +1 @@
-Subproject commit 28ac6b8788b3acc561c35c9946f73abb735c1df1
+Subproject commit 7b61cfd2e0c7bed6004f82d11b4cdc37a2e12cad