Update git submodules

* Update docs/submodules/bottlenecks from branch 'stable/fraser'
  - Lazy creation of VM pairs for soak throuputs tests

    Add the lazy creation progress of VM pairs while testing
    dataplane traffic using netperf

    Change-Id: I3228ff444ea074b99cb1afaec138191358064e40
    Signed-off-by: Yang Yu <Gabriel.yuyang@huawei.com>
    (cherry picked from commit 61aafcb0ca6cab9c25d2df7d409f4fa8716ebe5f)

diff --git a/docs/submodules/bottlenecks b/docs/submodules/bottlenecks
index 4828a4c..a863674 160000 (submodule)
--- a/docs/submodules/bottlenecks
+++ b/docs/submodules/bottlenecks
@@ -1 +1 @@
-Subproject commit 4828a4c36083c9409c97a4652d04a2d5f974d456
+Subproject commit a8636748fbf45bb3d8faa4f12e6b34cbd96ed599