Update git submodules

* Update docs/submodules/bottlenecks from branch 'stable/fraser'
  - bug-fix: image for VMs is wrongly referenced

    This patch is to fix the url of yardstick image for bottlenecks

    Change-Id: I7fca672e0a7b8976923162a12a8a752cec320fcb
    Signed-off-by: Yang Yu <Gabriel.yuyang@huawei.com>
    (cherry picked from commit 73bd5d30fb9d5ee3bc01d78b431282332a53b44d)

diff --git a/docs/submodules/bottlenecks b/docs/submodules/bottlenecks
index c4a33d0..4828a4c 160000 (submodule)
--- a/docs/submodules/bottlenecks
+++ b/docs/submodules/bottlenecks
@@ -1 +1 @@
-Subproject commit c4a33d033497629b5e0b2ef1b269742eb26b0502
+Subproject commit 4828a4c36083c9409c97a4652d04a2d5f974d456