Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Merge "Support to specify the valid external network name"
  - Support to specify the valid external network name

    In some deployments, the retrieved external network by the
    def get_external_networks in Snaps checked by "router:external"
    is not available. So it is necessary to specify the available
    external network as an env by user.

    Change-Id: I333e91dd106ed307541a9a197280199fde86bd30
    Signed-off-by: Linda Wang <wangwulin@huawei.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index f846018..11c2123 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit f8460182ebb264212f395e873594f84d41963243
+Subproject commit 11c21239ace9bd45abf4e79bb52dc13f06ae43ee