Update git submodules

* Update docs/submodules/clover from branch 'master'
  - Merge "Add visibility API in controller and CLI"
  - Add visibility API in controller and CLI

    - Modify get visibility to retrieve config and stats
    - Add visibility REST API in controller to clear, set, and
    get from redis
    - Add example yaml to set visibility (service list by name,
    metric suffixes/prefixes, and custom metrics) from CLI
    - Modify example yaml to start visibility (collector) for
    Istio 1.0 from CLI

    Change-Id: I43304ff6d70bb4b817b345b9c383ce3621fb06c7
    Signed-off-by: earrage <eddie.arrage@huawei.com>

diff --git a/docs/submodules/clover b/docs/submodules/clover
index 7f7c151..8541bdc 160000 (submodule)
--- a/docs/submodules/clover
+++ b/docs/submodules/clover
@@ -1 +1 @@
-Subproject commit 7f7c1519ccf71d26770bfa8ad97c333d78323075
+Subproject commit 8541bdcde5fdabf7689d2609adac982683b07558