Update git submodules

* Update docs/submodules/openretriever from branch 'master'
  - Merge "cleanup: remove fuel-plugin since fuel@opnfv use mccp"
  - cleanup: remove fuel-plugin since fuel@opnfv use mccp

    Change-Id: I42d9a9a187f7a709d44db36bb820087f726112bf
    Signed-off-by: Guo Ruijing <ruijing.guo@intel.com>

diff --git a/docs/submodules/openretriever b/docs/submodules/openretriever
index d2e76f3..b4804ed 160000 (submodule)
--- a/docs/submodules/openretriever
+++ b/docs/submodules/openretriever
@@ -1 +1 @@
-Subproject commit d2e76f3f7ae0d7da12f054cecddfbd344801ddc5
+Subproject commit b4804ed0b8d88fc91324dfbbf9e285d0691bb0f4