Update git submodules

* Update docs/submodules/stor4nfv from branch 'master'
  - Update the latest version of ansible script

    This patch is proposed for merging the latest version of
    ansible code according to opensds-installer project.
    From the latest version code, we change the default
    installation way from source code to release, which means
    there is no need for golang environment prepare and
    long-time building work.

    Change-Id: I93d7d24f29e61979bc8fda7125ae753063eda423
    Signed-off-by: leonwang <wanghui71@huawei.com>

diff --git a/docs/submodules/stor4nfv b/docs/submodules/stor4nfv
index 078bb83..91a8433 160000 (submodule)
--- a/docs/submodules/stor4nfv
+++ b/docs/submodules/stor4nfv
@@ -1 +1 @@
-Subproject commit 078bb837513f3b83fdd07f2e10f9abeb0bd485db
+Subproject commit 91a84330494b100ac9077652c910fb248f737717