Update git submodules

* Update docs/submodules/bottlenecks from branch 'master'
  - Merge "Docs for Danube 3"
  - Docs for Danube 3

    JIRA: BOTTLENECKS-137

    Documentation for Danube 3

    Change-Id: Ic4b2611028fa45c0b731e998296e5000e35a33f6
    Signed-off-by: yuyang <Gabriel.yuyang@huawei.com>

diff --git a/docs/submodules/bottlenecks b/docs/submodules/bottlenecks
index 6de46e9..c6647e5 160000 (submodule)
--- a/docs/submodules/bottlenecks
+++ b/docs/submodules/bottlenecks
@@ -1 +1 @@
-Subproject commit 6de46e9144ee0bc2962460c600e4b3a888d934ef
+Subproject commit c6647e559cddfe8bdf064bf69edd970df4044ce5