Update git submodules

* Update docs/submodules/releng from branch 'master'
  - support fuel installer for doctor test

    As currently fuel doesn't integrate with Congress, we only support sample inspector.

    Change-Id: I4a3742f019bdd3c0e666ed5f18f456793a6edbc0
    Signed-off-by: dongwenjuan <dong.wenjuan@zte.com.cn>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 8428109..c4730a0 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 8428109135870ffb3b29cc3f1748458ca576396e
+Subproject commit c4730a0a8689c8eb5f8606ddebb4aa44e722f77a