Update git submodules

* Update docs/submodules/bottlenecks from branch 'stable/euphrates'
  - support hosts file copy

    JIRA: BOTTLENECK-227

    Dovetail needs to regulate the hosts file of each docker to
    adapt SUTs. This patch is to make hosts file consistant in
    Bottlenecks-Yarstick docker.

    Change-Id: I93a57a5cac9c8d8c0a8b6660e84b8b351c455786
    Signed-off-by: Yang Yu <Gabriel.yuyang@huawei.com>
    (cherry picked from commit b8b65fbc102f632a1c83cd3fc67dc2b921902a8a)

diff --git a/docs/submodules/bottlenecks b/docs/submodules/bottlenecks
index 9efc276..e8796c3 160000 (submodule)
--- a/docs/submodules/bottlenecks
+++ b/docs/submodules/bottlenecks
@@ -1 +1 @@
-Subproject commit 9efc27665e10b4a36153291e171efdd8bf10c11b
+Subproject commit e8796c31a6cd66da49082f0535dd4fbee9aaebb3