Update git submodules

* Update docs/submodules/clover from branch 'master'
  - Merge "Cover validation of elasticsearch cluster"
  - Cover validation of elasticsearch cluster

    - cluster health is not red
    - indics found
    - log entry created by istio found
    - requests in and out http load balance matches

    pytest is used as the test runner and wrapped in `validate.py`

    Change-Id: Iad540b69d05118fadc97df679cf3424513c15e38
    Signed-off-by: Yujun Zhang <zhang.yujunz@zte.com.cn>

diff --git a/docs/submodules/clover b/docs/submodules/clover
index eec41c3..af5f78f 160000 (submodule)
--- a/docs/submodules/clover
+++ b/docs/submodules/clover
@@ -1 +1 @@
-Subproject commit eec41c3e79d3cfe8611d705e80af8c2b60641683
+Subproject commit af5f78f5221c5b55cff1c45fa4f5a879a772b796