Update git submodules

* Update docs/submodules/clover from branch 'master'
  - clover fraser: preliminary documents checkin

    * add preliminary Clover Fraser release notes
    * add preliminary Clover Fraser user guide

    Change-Id: I84b0ae1538aaa175245dd47d90ac2343eaa26cc4
    Signed-off-by: Stephen Wong <stephen.kf.wong@gmail.com>

diff --git a/docs/submodules/clover b/docs/submodules/clover
index 7866147..721d284 160000 (submodule)
--- a/docs/submodules/clover
+++ b/docs/submodules/clover
@@ -1 +1 @@
-Subproject commit 7866147838e83a479c1c158eebfd08ff35d17f3c
+Subproject commit 721d284c2147c9565a10e17beedf6da81722728c