Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Functest: Introduce building image job for euphrates"
  - Functest: Introduce building image job for euphrates

    Change-Id: I9e4aab444490b7a85d2fd24344045452a62a0bcc
    Signed-off-by: Linda Wang <wangwulin@huawei.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index c8e4cda..55746e5 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit c8e4cda4f9a435792331658bcc9c2b70eddfc9b8
+Subproject commit 55746e543b9a56d7648d28620db90688cc2ed3d8