Update git submodules

* Update docs/submodules/functest from branch 'stable/danube'
  - rename tempest.conf to refstack_tempest.conf

    since for tempest smoke/full, etc, will also use a file named
    tempest.conf this wil cover the refstack tempest.conf,
    rename it to refstack_tempest.conf, then easily for users to
    debug to check if the configure file is correct or not.

    Change-Id: Ic2f93fb05effb1a61276cb6ba755076a0404caad
    Signed-off-by: MatthewLi <matthew.lijun@huawei.com>
    (cherry picked from commit 8bbfda2df0a3a10d069a41c0f074b0de69737767)

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 4af24ab..2c48dfc 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 4af24ab61703bca05a37c062388390ac82d5c96e
+Subproject commit 2c48dfc2b32c577c4754c2f1df2e6becc9bf5af3