Update git submodules

* Update docs/submodules/sdnvpn from branch 'master'
  - Merge "Remove argparse for adding argument -r"
  - Remove argparse for adding argument -r

    Change-Id: Iaa2ddc3f655a2bf85785a99a519e0df78c298037
    Signed-off-by: Linda Wang <wangwulin@huawei.com>

diff --git a/docs/submodules/sdnvpn b/docs/submodules/sdnvpn
index 6f4fa99..4245d81 160000 (submodule)
--- a/docs/submodules/sdnvpn
+++ b/docs/submodules/sdnvpn
@@ -1 +1 @@
-Subproject commit 6f4fa990aec1d58d39930311640cd6f086e5b696
+Subproject commit 4245d81de9226f64321dcd828e2a91ac912cf7d7